(7) Lesson 4.5 - Add and Subtract Mixed Numbers

1. Course 2, Lesson 4-5
Add or subtract. Write in simplest form.
1. 2.
3. Evaluate + s if s = .
4. Jared and his friend Andre ordered a pizza. Jared ate of the pizza and
Andre ate of the pizza. How much more of the pizza did Jared eat?
5. Ellen has of a jar of jelly. After she makes some peanut butter and jelly
sandwiches, of the jar of jelly is left. What part of the jar of jelly did Ellen
use?

7
10
1
5

+
1
7
2
3
1
10
3
5
2
5
1
3
3
4
2
5

2. Course 2, Lesson 4-5
ANSWERS
1.
2.
3.
4. Jared ate more of the pizza.
5.
1
2
11
21
7
10
1
15
7
20

3. WHAT happens when you add,
subtract, multiply, and divide
fractions?
The Number System
Course 2, Lesson 4-5

4. Course 2, Lesson 4-5 Common Core State Standards © Copyright 2010. National Governors Association Center for Best Practices and Council of
Chief State School Officers. All rights reserved.
The Number System
• 7.NS.1 Apply and extend previous understandings of addition and
subtraction to add and subtract rational numbers; represent addition
and subtraction on a horizontal or vertical number line diagram.
• 7.NS.1d Apply properties of operations as strategies to add and
subtract rational numbers.
• 7.NS.3 Solve real-world and mathematical problems involving the four
operations with rational numbers.

5. Course 2, Lesson 4-5 Common Core State Standards © Copyright 2010. National Governors Association Center for Best Practices and Council of
Chief State School Officers. All rights reserved.
The Number System
• 7.EE.3 Solve multi-step real-life and mathematical problems posed with
positive and negative rational numbers in any form (whole numbers,
fractions, and decimals), using tools strategically. Apply properties of
operations to calculate with numbers in any form; convert between
forms as appropriate; and assess the reasonableness of answers using
mental computation and estimation strategies.
Mathematical Practices
1 Make sense of problems and persevere in solving them.
3 Construct viable arguments and critique the reasoning of others.
4 Model with mathematics.

6. • To add mixed numbers
• To subtract mixed numbers
• To solve real-world problems involving
the addition or subtraction of rational
numbers
Course 2, Lesson 4-5
The Number System

7. 1
Need Another Example?
2
3
Step-by-Step Example
1. Find 7 + 10 . Write in simplest form.
Simplify.
Add the whole numbers and fractions separately.
Estimate 7 + 10 = 17
Check for Reasonableness

8. Answer
Need Another Example?
Find 3 + 4 . Write in simplest form.

9. 1
Need Another Example?
2
3
Step-by-Step Example
2. Find 8 – 2 . Write in simplest form.
Simplify.
Rename the fraction using the LCD. Then subtract.
Estimate 9 – 2 = 7
Check for Reasonableness

10. Answer
Need Another Example?
Find 9 – 4 . Write in simplest form.

11. 1
Need Another Example?
2
3
4
5 6
Step-by-Step Example
3. Find 2 – 1 .
Simplify.
Subtract the whole numbers and then the fractions.
Estimate
Check for Reasonableness
Rename Mixed Numbers
Since is less than ,
rename 2 before
subtracting. =
Change 1 to .
3
3
Write 2 as 1 .
≈
Write as Improper Fractions
Write 2 as .
Write 1 as .
So, 2 – 1 = .
Using either method, the
answer is .

12. Answer
Need Another Example?
Find 8 – 3 . Write in simplest form.

13. Need Another Example?
Step-by-Step Example
4. An urban planner is designing a skateboard park.
The length of the skateboard park is 120 feet.
The length of the parking lot is 40 feet. What will
be the length of the park and the parking lot
combined?
1
2
3
4
Rename as and as .120 + 40 = 120 + 40
= 160 + Add the whole numbers and fractions separately.
Simplify.= 160
The total length is 160 feet.

14. Answer
Need Another Example?
41 ft
Marlee is making necklaces and bracelets for a class
craft sale. She uses 25 feet of string for the
necklaces and 15 feet of string for the bracelets.
What is the total length of string that Marlee used?

15. How did what you learned
today help you answer the
WHAT happens when you add,
subtract, multiply, and divide fractions?
Course 2, Lesson 4-5
The Number System

16. How did what you learned
today help you answer the
WHAT happens when you add,
subtract, multiply, and divide fractions?
Course 2, Lesson 4-5
The Number System
Sample answers:
• When you add or subtract mixed numbers you can
rename the mixed number of write it as an improper
fraction.
• I also learned to choose an operation to solve real-
world problem involving mixed numbers

17. Write the mathematical
procedures you would
use to find .
Course 2, Lesson 4-5
Ratios and Proportional RelationshipsThe Number System
1 59 -6
3 8