diff --git a/lab-python-lambda-map-reduce-filter.ipynb b/lab-python-lambda-map-reduce-filter.ipynb
index 96c9781..3a37fa8 100644
--- a/lab-python-lambda-map-reduce-filter.ipynb
+++ b/lab-python-lambda-map-reduce-filter.ipynb
@@ -66,7 +66,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 13,
    "id": "08463071-9351-4d49-8d29-4fcb817fb177",
    "metadata": {},
    "outputs": [],
@@ -94,12 +94,59 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 12,
    "id": "0781335d-39cf-403d-b86a-ca908a09fe55",
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Debits: [(-1200, 'debit'), (-100, 'debit'), (-250, 'debit'), (-300, 'debit'), (-850, 'debit')]\n",
+      "Credits: [(2500, 'credit'), (850, 'credit'), (1500, 'credit'), (5000, 'credit'), (1000, 'credit')]\n"
+     ]
+    }
+   ],
    "source": [
-    "# your code goes here"
+    "# your code goes here\n",
+    "\n",
+    "# Challenge 1. Exercise 1:\n",
+    "\n",
+    "# use the following data, which is a list of bank transactions:\n",
+    "# transactions = [(-1200, 'debit'), (2500, 'credit'), (-100, 'debit'), (850, 'credit'), (-250, 'debit'), (1500, 'credit'), (-300, 'debit'), (5000, 'credit'), (-850, 'debit'), (1000, 'credit')]\n",
+    "# Create a new list called credits that includes all of the debit transactions from the list transactions.\n",
+    "# Use the filter() function to create a new list called debits.\n",
+    "\n",
+    "transactions = [(-1200, 'debit'), (2500, 'credit'), (-100, 'debit'), (850, 'credit'), (-250, 'debit'), (1500, 'credit'), (-300, 'debit'), (5000, 'credit'), (-850, 'debit'), (1000, 'credit')]\n",
+    "\n",
+    "debits = list(filter(lambda x: x[1] == 'debit', transactions))\n",
+    "credits = list(filter(lambda x: x[1] == 'credit', transactions))\n",
+    "print(\"Debits:\", debits)\n",
+    "print(\"Credits:\", credits)\n"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "3a20fc61",
+   "metadata": {},
+   "source": [
+    "#### **Note on the exercise interpretation**\n",
+    "\n",
+    "The exercise statement says:  \n",
+    "> *\"Create a new list called credits that includes all of the debit transactions.\"*\n",
+    "\n",
+    "Taken literally, this would result in:\n",
+    "- a list called `credits` containing **debit** transactions, and  \n",
+    "- another list called `debits` also containing **debit** transactions,\n",
+    "\n",
+    "which does not make logical sense given the context.\n",
+    "\n",
+    "For this reason, I assumed there is a typo in the statement and interpreted the task as:\n",
+    "- `credits` → transactions with type `\"credit\"`\n",
+    "- `debits` → transactions with type `\"debit\"`\n",
+    "\n",
+    "From my perspective, this interpretation is consistent with the variable names, the domain logic, and the intended learning objective of the lab.  \n",
+    "I appreciate feedback if a different interpretation was intended.\n"
    ]
   },
   {
@@ -127,9 +174,75 @@
    "execution_count": null,
    "id": "25073469-7258-4fc6-b0a0-ef8ea57688fe",
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Sorted Debits: [(-100, 'debit'), (-250, 'debit'), (-300, 'debit'), (-850, 'debit'), (-1200, 'debit')]\n"
+     ]
+    }
+   ],
+   "source": [
+    "# your code goes here\n",
+    "\n",
+    "# Challenge 1. Exercise 2:\n",
+    "\n",
+    "# Create a new list that includes all of the debit transactions from the list transactions, sorted in descending order by amount.\n",
+    "\n",
+    "# Use the previously created debits list.\n",
+    "transactions = [(-1200, 'debit'), (2500, 'credit'), (-100, 'debit'), (850, 'credit'), (-250, 'debit'), (1500, 'credit'), (-300, 'debit'), (5000, 'credit'), (-850, 'debit'), (1000, 'credit')]\n",
+    "\n",
+    "# Define a lambda function called sort_descending \n",
+    "# that takes two tuples and returns True if the transaction amount of the first tuple is greater than the transaction amount of the second tuple.\n",
+    "sort_descending = lambda x, y: x[0] > y[0]\n",
+    "\n",
+    "# Use the sorted() function with sort_descending and debits to create a new list.\n",
+    "debits = list(filter(lambda x: x[1] == 'debit', transactions))\n",
+    "sorted_debits = sorted(debits, key=lambda x: x[0], reverse=True)\n",
+    "print(\"Sorted Debits:\", sorted_debits)\n",
+    "\n",
+    "# expected output: [(-100, 'debit'), (-250, 'debit'), (-300, 'debit'), (-850, 'debit'), (-1200, 'debit')]\n",
+    "\n",
+    "# This solution uses key + reverse in sorted()."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 16,
+   "id": "5497bccc",
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Sorted Debits: [(-100, 'debit'), (-250, 'debit'), (-300, 'debit'), (-850, 'debit'), (-1200, 'debit')]\n"
+     ]
+    }
+   ],
    "source": [
-    "# your code goes here"
+    "# your code goes here\n",
+    "\n",
+    "# Challenge 1. Exercise 2:\n",
+    "\n",
+    "# Create a new list that includes all of the debit transactions from the list transactions, sorted in descending order by amount.\n",
+    "\n",
+    "# Use the previously created debits list.\n",
+    "# Define a lambda function called sort_descending \n",
+    "# that takes two tuples and returns True if the transaction amount of the first tuple is greater than the transaction amount of the second tuple.\n",
+    "# Use the sorted() function with sort_descending and debits to create a new list.\n",
+    "\n",
+    "from functools import cmp_to_key\n",
+    "transactions = [(-1200, 'debit'), (2500, 'credit'), (-100, 'debit'), (850, 'credit'), (-250, 'debit'), (1500, 'credit'), (-300, 'debit'), (5000, 'credit'), (-850, 'debit'), (1000, 'credit')]\n",
+    "debits = list(filter(lambda x: x[1] == 'debit', transactions))\n",
+    "sort_descending = lambda x, y: -1 if x[0] > y[0] else (1 if x[0] < y[0] else 0)\n",
+    "sorted_debits = sorted(debits, key=cmp_to_key(sort_descending))\n",
+    "print(\"Sorted Debits:\", sorted_debits)\n",
+    "\n",
+    "# expected output: [(-100, 'debit'), (-250, 'debit'), (-300, 'debit'), (-850, 'debit'), (-1200, 'debit')]\n",
+    "\n",
+    "# This solution uses comparator comp_to_key with sorted()."
    ]
   },
   {
@@ -137,7 +250,7 @@
    "id": "bee57a6e-19a3-4708-9b70-3b41a215353f",
    "metadata": {},
    "source": [
-    "## Challenge 2:  Interest Calculation"
+    "## Challenge 2:  Interest Calculation "
    ]
   },
   {
@@ -169,12 +282,33 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 1,
    "id": "2f253b7e-5300-4819-b38f-9fc090554f51",
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Balances after interest: [105.0, 52.5, -26.25, 1050.0, -10.5]\n"
+     ]
+    }
+   ],
    "source": [
-    "# your code goes here"
+    "# your code goes here\n",
+    "\n",
+    "# Write Python code to take a list of bank account balances\n",
+    "# and returns a new list containing the balance after one year of interest has been added.\n",
+    "# Use the map function to apply this function to the list of bank accounts\n",
+    "# and take an interest rate of 0.05.\n",
+    "\n",
+    "balances = [100, 50, -25, 1000, -10]\n",
+    "\n",
+    "def add_interest(balance):\n",
+    "    return balance + (balance * 0.05)\n",
+    "\n",
+    "interest_balances = list(map(add_interest, balances))\n",
+    "print(\"Balances after interest:\", interest_balances)\n"
    ]
   },
   {
@@ -195,7 +329,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 3,
    "id": "69e24c3b-385e-44d6-a8ed-705a3f58e696",
    "metadata": {},
    "outputs": [],
@@ -209,12 +343,37 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 4,
    "id": "0906a9b0-d567-4786-96f2-5755611b885e",
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Accounts after interest: [{'balance': 1020.0, 'interest_rate': 0.02}, {'balance': 2020.0, 'interest_rate': 0.01}, {'balance': 515.0, 'interest_rate': 0.03}]\n"
+     ]
+    }
+   ],
    "source": [
-    "# your code goes here\n"
+    "# your code goes here\n",
+    "\n",
+    "# Write Python code to take a list of bank account dictionaries,\n",
+    "# each containing the account balance and interest rate,\n",
+    "# and returns a new list of dictionaries containing the balance after one year of interest has been added.\n",
+    "# Use the map function to apply this function to the list of bank accounts.\n",
+    "\n",
+    "accounts = [\n",
+    "    {'balance': 1000, 'interest_rate': 0.02},\n",
+    "    {'balance': 2000, 'interest_rate': 0.01},\n",
+    "    {'balance': 500, 'interest_rate': 0.03},\n",
+    "]\n",
+    "\n",
+    "def add_interest_account(account):\n",
+    "    new_balance = account['balance'] + (account['balance'] * account['interest_rate'])\n",
+    "    return {'balance': new_balance, 'interest_rate': account['interest_rate']}\n",
+    "interest_accounts = list(map(add_interest_account, accounts))\n",
+    "print(\"Accounts after interest:\", interest_accounts)\n"
    ]
   },
   {
@@ -246,11 +405,82 @@
    "execution_count": null,
    "id": "6284dbd3-e117-411e-8087-352be6deaed4",
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Balances after interest: [105.0, 52.5, -26.25, 1050.0, -10.5]\n",
+      "Total negative balances: -36.75\n"
+     ]
+    }
+   ],
+   "source": [
+    "from functools import reduce\n",
+    "\n",
+    "# your code goes here\n",
+    "\n",
+    "# Write Python code to take the new list of bank account balances \n",
+    "# (balances list after applying an interest_rate of 0.05,\n",
+    "# result of Challenge 1 Exercise 1), new_balance = [105.0, 52.5, -26.25, 1050.0, -10.5]\n",
+    "# and print the total amount of negative balances. Use filter and reduce function.\n",
+    "\n",
+    "balances = [100, 50, -25, 1000, -10]\n",
+    "\n",
+    "def add_interest(balance):\n",
+    "    return balance + (balance * 0.05)\n",
+    "\n",
+    "interest_balances = list(map(add_interest, balances))\n",
+    "print(\"Balances after interest:\", interest_balances)\n",
+    "\n",
+    "negative_balances = list(filter(lambda x: x < 0, interest_balances))\n",
+    "total_negative = reduce(lambda x, y: x + y, negative_balances)\n",
+    "print(\"Total negative balances:\", total_negative)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "id": "935219e4",
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Total negative balances: -36.75\n"
+     ]
+    }
+   ],
    "source": [
     "from functools import reduce\n",
     "\n",
-    "# your code goes here"
+    "# your code goes here\n",
+    "\n",
+    "# Write Python code to take the new list of bank account balances \n",
+    "# (balances list after applying an interest_rate of 0.05,\n",
+    "# result of Challenge 1 Exercise 1), # new_balance = [105.0, 52.5, -26.25, 1050.0, -10.5]\n",
+    "# and print the total amount of negative balances. Use filter and reduce function.\n",
+    "\n",
+    "balances = [100, 50, -25, 1000, -10]\n",
+    "\n",
+    "new_balance = [105.0, 52.5, -26.25, 1050.0, -10.5]\n",
+    "\n",
+    "negative_balances = list(filter(lambda x: x < 0, new_balance))\n",
+    "total_negative = reduce(lambda x, y: x + y, negative_balances)\n",
+    "print(\"Total negative balances:\", total_negative)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "848584f2",
+   "metadata": {},
+   "source": [
+    "**Note on exercise interpretation:**\n",
+    ">\n",
+    "> While working on this exercise, I noticed a potential inconsistency in the exercise reference. The statement mentions Challenge 1, Exercise 1; however, based on the overall structure and logic of the lab, that exercise focuses on list creation rather than balance calculations.\n",
+    "For this reason, I assumed that the intended reference was the exercise involving balance transformations, and I proceeded by using the balances obtained in the corresponding balance-related exercise, applying the required operations (filter and reduce) as instructed.\n",
+    "This interpretation was made to ensure logical consistency across the lab. I am, of course, open to feedback in case a different interpretation was intended.\n"
    ]
   },
   {
@@ -273,10 +503,18 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 9,
    "id": "da2264b5-298e-4b45-99df-852b94e90d15",
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Remaining balances: [650, 1600, 275]\n"
+     ]
+    }
+   ],
    "source": [
     "accounts = [\n",
     "    {'balance': 1000, 'withdrawals': [100, 50, 200]},\n",
@@ -284,13 +522,25 @@
     "    {'balance': 500, 'withdrawals': [50, 100, 75]},\n",
     "]\n",
     "\n",
-    "# your code goes here\n"
+    "# your code goes here\n",
+    "\n",
+    "# Write a Python function called calculate_balance that takes a bank account dictionary as an argument\n",
+    "# and returns the remaining balance after subtracting all the withdrawals.\n",
+    "# Then, use the map function and the calculate_balance function to apply it to the list accounts. \n",
+    "# This should give you a list of remaining balances after all the withdrawals have been subtracted.\n",
+    "\n",
+    "def calculate_balance(account):\n",
+    "    total_withdrawals = sum(account['withdrawals'])\n",
+    "    return account['balance'] - total_withdrawals\n",
+    "\n",
+    "remaining_balances = list(map(calculate_balance, accounts))\n",
+    "print(\"Remaining balances:\", remaining_balances)"
    ]
   }
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 3 (ipykernel)",
+   "display_name": "base",
    "language": "python",
    "name": "python3"
   },
@@ -304,7 +554,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.13"
+   "version": "3.13.5"
   }
  },
  "nbformat": 4,