Solved Exercises on Money Word Problems Addition and Subtraction in Grade 3

Master money calculations: addition and subtraction with coins and bills through these 5 detailed exercises.

Solution: Exercises 1 to 3
1 Adding Money
Exercise 1
Alex earned $4.75 from mowing lawns. His dad gave him $3.50 for his birthday. How much money does Alex have now?
Definition:

Addition: Combining two or more amounts to find the total

Addition method:
  1. Align the decimal points when adding dollars and cents
  2. Add the cents column first
  3. Add the dollars column
  4. Carry over if necessary
Earnings
$4.75
Gift
$3.50
Total
$4.75 + $3.50 = $8.25
Step 1: Write amounts vertically

$4.75
+ $3.50

Step 2: Add the cents

75¢ + 50¢ = 125¢ = $1.25

Step 3: Add the dollars

$4 + $3 + $1 (carried over) = $8

Step 4: Combine dollars and cents

$8 + $0.25 = $8.25

Visual: $4.75 + $3.50 = $8.25

$4.75 + $3.50 = $8.25
Final answer:

Alex has $8.25 now

Applied rules:

• Decimal Alignment: Align decimal points when adding

• Carrying: When cents exceed 100, carry over to dollars

• Verification: $8.25 - $3.50 = $4.75 ✓

2 Subtracting Money
Exercise 2
Maya had $10.00. She bought a book for $6.45. How much money does she have left?
Definition:

Subtraction: Taking away one amount from another

Starting Amount
$10.00
Amount Spent
$6.45
Remaining
$10.00 - $6.45 = $3.55
Step 1: Write amounts vertically

$10.00
- $6.45

Step 2: Borrow if needed

$10.00 becomes $9.100¢ (since we need to borrow)

Step 3: Subtract the cents

100¢ - 45¢ = 55¢

Step 4: Subtract the dollars

$9 - $6 = $3

Visual: $10.00 - $6.45 = $3.55

$10.00 - $6.45 = $3.55
Final answer:

Maya has $3.55 left

Applied rules:

• Borrowing: When subtracting, borrow from the next place value

• Decimal Alignment: Align decimal points when subtracting

• Verification: $3.55 + $6.45 = $10.00 ✓

3 Mixed Operations
Exercise 3
Sam earned $5.25 from babysitting. He spent $2.80 on snacks and then earned $3.75 more from helping neighbors. How much money does he have now?
Definition:

Mixed Operations: Problems involving both addition and subtraction

Started With
$5.25
Spent
-$2.80
Earned More
+$3.75
Step 1: Calculate after first transaction

$5.25 - $2.80 = $2.45

Step 2: Calculate final amount

$2.45 + $3.75 = $6.20

Step 3: Alternative method

Total earned: $5.25 + $3.75 = $9.00

Total spent: $2.80

Final amount: $9.00 - $2.80 = $6.20

Visual: $5.25 - $2.80 + $3.75 = $6.20

$5.25 - $2.80 + $3.75 = $6.20
Final answer:

Sam has $6.20 now

Applied rules:

• Order of Operations: Perform operations from left to right

• Alternative Method: Group additions and subtractions separately

• Verification: Check by working backwards

Money Addition and Subtraction Methods
\(\text{Addition}: A + B = C\)
Adding Money
\(\text{Subtraction}: A - B = C\)
Subtracting Money
Addition Rule
Combine amounts
Use when getting more money
Subtraction Rule
Take away amounts
Use when spending money
Borrowing Rule
Borrow from next place
When subtracting and need more
➕
Addition: Getting more money
➖
Subtraction: Spending money
Solution: Exercises 4 to 5
4 Making Change
Exercise 4
Lisa paid $20.00 for school supplies that cost $14.65. How much change should she receive?
Definition:

Change: The money returned when you pay more than the cost

Amount Paid
$20.00
Cost
$14.65
Change
$20.00 - $14.65 = $5.35
Step 1: Set up the subtraction

$20.00 - $14.65

Step 2: Borrow if needed

$20.00 = $19.100¢

Step 3: Subtract the cents

100¢ - 65¢ = 35¢

Step 4: Subtract the dollars

$19 - $14 = $5

Visual: $20.00 - $14.65 = $5.35

$20.00 - $14.65 = $5.35
Final answer:

Lisa should receive $5.35 in change

Applied rules:

• Change Formula: Paid - Cost = Change

• Borrowing: When cents in the top number are less than bottom number

• Verification: $14.65 + $5.35 = $20.00 ✓

5 Saving and Spending
Exercise 5
James saved $12.50 over four weeks. In the fifth week, he spent $4.75 on a toy. Then he earned $6.25 from doing extra chores. How much does he have now?
Definition:

Multi-step Problem: A problem requiring multiple operations to solve

Started With
$12.50
Spent
-$4.75
Earned
+$6.25
Step 1: Calculate after spending

$12.50 - $4.75 = $7.75

Step 2: Calculate final amount

$7.75 + $6.25 = $14.00

Step 3: Verify with alternative method

Total earnings: $12.50 + $6.25 = $18.75

Total spent: $4.75

Final: $18.75 - $4.75 = $14.00 ✓

Visual: $12.50 - $4.75 + $6.25 = $14.00

$12.50 - $4.75 + $6.25 = $14.00
Final answer:

James has $14.00 now

Applied rules:

• Sequential Operations: Perform operations in order given

• Alternative Verification: Group similar operations to check

• Place Value: Keep track of dollars and cents separately

Money Addition and Subtraction Strategies
\(\text{Change} = \text{Paid} - \text{Cost}\)
Making Change
Key definitions:

Addition: Combining amounts to find a total

Subtraction: Taking away one amount from another

Decimal Alignment: Keeping decimal points in the same column

Borrowing: Taking from the next place value when subtracting

Addition and subtraction methodology:
  1. Read the problem: Understand what operation is needed
  2. Identify amounts: Find all the dollar and cent amounts
  3. Align decimals: Write numbers with decimal points aligned
  4. Perform operation: Add or subtract column by column
  5. Check answer: Verify with inverse operation
Tip 1: Always align decimal points when adding or subtracting money.
Tip 2: When subtracting, borrow from the next place value if needed.
Tip 3: Verify addition by subtracting one addend from the sum.
Tip 4: Verify subtraction by adding the difference to the subtrahend.
Common errors: Misaligning decimals, forgetting to borrow, mixing dollars and cents incorrectly.
Practice strategies: Work with real money, practice decimal alignment, solve multi-step problems.
Addition and subtraction formulas:

• Addition: Amount₁ + Amount₂ = Total

• Subtraction: Starting - Spent = Remaining

• Change: Paid - Cost = Change

• Borrowing: When subtracting, borrow from next place value

Questions & Answers

Question: I get confused when I have to subtract money and need to borrow. How do I know when to borrow?

Answer: You need to borrow when the top number in a column is smaller than the bottom number:

  • When subtracting cents: If the top cent amount is less than the bottom
  • When subtracting dollars: If the top dollar amount is less than the bottom
  • Borrow 1 from the next higher place value (turn it into 10 of the current place)

Example: $10.00 - $6.45

• Top cents (0) is less than bottom cents (45), so borrow 1 dollar = 100 cents

• Now it becomes $9.100¢ - $6.45¢ = $3.55

Question: My child struggles with multi-step money problems. What's the best approach?

Answer: Break multi-step problems into smaller parts:

  • Read slowly: Identify each transaction (earnings, spending, etc.)
  • Work sequentially: Solve one step at a time
  • Keep track: Write down intermediate results
  • Check progress: Verify each step before moving to the next

Example: Save $5, spend $2, earn $3

• Step 1: $0 + $5 = $5

• Step 2: $5 - $2 = $3

• Step 3: $3 + $3 = $6

Question: How do I teach students to verify their addition and subtraction answers?

Answer: Use inverse operations to verify answers:

  • For addition: Subtract one addend from the sum to get the other addend
  • For subtraction: Add the difference to the subtrahend to get the minuend
  • For change problems: Add the change to the cost to get the amount paid

Example: $5.25 + $3.75 = $9.00

• Verification: $9.00 - $3.75 = $5.25 ✓

Example: $20.00 - $14.65 = $5.35

• Verification: $5.35 + $14.65 = $20.00 ✓

Comprehensive Summary: Money Word Problems Addition and Subtraction
Key Concepts and Definitions:

Addition: Combining two or more amounts to find a total (symbol: +)

Subtraction: Taking away one amount from another (symbol: -)

Decimal Alignment: Keeping decimal points in the same vertical column

Borrowing: Taking from the next place value when subtracting

Multi-step Problems: Problems requiring more than one operation to solve

Core Rules and Principles:

• Decimal Alignment: Always align decimal points when adding or subtracting

• Borrowing Rule: When the top number is smaller, borrow from the next place value

• Operation Selection: Addition for getting more money, subtraction for spending money

• Verification: Use inverse operations to check your answer

Step-by-Step Addition Method:
  1. Align decimals: Write numbers with decimal points lined up
  2. Add cents: Add the hundredths and tenths columns
  3. Add dollars: Add the ones and tens columns
  4. Carry over: If cents total exceeds 100, carry to dollars
  5. Verify: Check by subtracting one addend from the sum
Step-by-Step Subtraction Method:
  1. Align decimals: Write numbers with decimal points lined up
  2. Check for borrowing: See if top number is smaller than bottom
  3. Borrow if needed: Take from next place value
  4. Subtract: Subtract column by column
  5. Verify: Check by adding the difference to the subtrahend
Tip 1: Always align decimal points when working with money.
Tip 2: When borrowing, turn 1 dollar into 100 cents.
Tip 3: For multi-step problems, solve one step at a time.
Tip 4: Always verify your answer using the opposite operation.
Common Pitfalls: Misaligning decimals, forgetting to borrow, mixing up addition and subtraction.
Practice Strategies: Use real money for practice, work with word problems, verify answers.
Key Takeaways for Students:

• Always align decimal points when adding or subtracting money

• Use addition when getting more money, subtraction when spending money

• When subtracting, borrow from the next place value if needed

• Verify your answer using the opposite operation

• For multi-step problems, solve one step at a time