3-7 Adding and Subtracting Fractions

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3-7 Adding and Subtracting Fractions

Learn to add and subtract fractions.

3-7 Adding and Subtracting Fractions

Add. Write the answer in simplest form.

Additional Example 1A: Adding or Subtracting Fractions with Like Denominators

58

+ 18

58

+ 18

= 5 + 18

Add the numerators and keepthe denominator.

= 68

= 34 Simplify.

3-7 Adding and Subtracting Fractions

Subtract. Write the answer in simplest form.

Additional Example 1B: Adding or Subtracting Fractions with Like Denominators

911

– 411

911

–4

11= 9 – 4

11Subtract the numerators andkeep the denominator.

The answer is in the simplestform.

= 5 11

3-7 Adding and Subtracting Fractions

Add. Write the answer in simplest form.

Check It Out: Example 1A

56

+ 16

56

+ 16

= 5 + 16

Add the numerators and keepthe denominator.

= 66

= 1 Simplify.

3-7 Adding and Subtracting Fractions

Subtract. Write the answer in simplest form.

Check It Out: Example 1B

710

– 410

710

–4

10= 7 – 4

10Subtract the numerators andkeep the denominator.

The answer is in the simplestform.

= 3 10

3-7 Adding and Subtracting Fractions

Additional Example 1: Measurement Application

Kevin is 48 inches tall. His brother Keith is 538

58

inches taller. How tall is Keith ?

4838

+558

= 53 88

+Add the integers and add the fractions.

= 53 + 1 Rewrite88 as 1.

54 inches tall.

A mixed number is the sum of an integer and a fraction: 3 = 3 + .

Helpful Hint

45

45

3-7 Adding and Subtracting Fractions

Check It Out: Example 1

Alvin weighs 72 lbs. His baby brother weighs 15 lbs. How much do they weigh together?

7223

+ 1513

= 87 33

+ Add the integers and add the fractions.

= 87 + 1 Rewrite33 as 1.

Together they weigh 88 pounds.

231

3

3-7 Adding and Subtracting Fractions

Standard Lesson Quiz

Lesson Quizzes

Lesson Quiz for Student Response Systems

3-8 Adding and Subtracting Mixed Numbers

Add. Write the answer in simplest form.

Additional Example 2A: Adding Mixed Numbers

9 23

+ 12 23

923

+ 12 23

= 21 + 43

Add the fractions and then add the integers.

= 21 + 1 13

Rewrite the improper fraction as a mixed number. Add= 22 1

3Helpful Hint

Add the fractions first in case an improper fraction needs to be rewritten.

3-7 Adding and Subtracting Fractions

Lesson QuizAdd or subtract. Write each answer in simplest form.

112

13

2. 38

+ 58

1. 57

– 37

3. 4.12

– 14

5. You need a nail to go through a -inch door

and extend an extra inch. How long should the nail be?

114

778

1

in.118

27

+512

1112

3-7 Adding and Subtracting Fractions

1. Add. Write your answer in simplest form.

+

A. 0 C.

B. D. 1

Lesson Quiz for Student Response Systems

1 2

1 9

4 9

5 9

3-7 Adding and Subtracting Fractions

2. Subtract. Write your answer in simplest form.

–

A. C.

B. or 1 D. 1

Lesson Quiz for Student Response Systems

4 11

14 11

3 11

4 11

3 11

9 11

5 11

3-7 Adding and Subtracting Fractions

3. Add. Write your answer in simplest form.

+

A. C.

B. D. or 1

Lesson Quiz for Student Response Systems

4 11

3 11

17

2424

17

3 8

1 3

7 17

3-7 Adding and Subtracting Fractions

4. Subtract. Write your answer in simplest form.

–

A. C.

B. D. or 4

Lesson Quiz for Student Response Systems

4 7

6 7

13

6060

13

5 12

1 5

8 13

3-7 Adding and Subtracting Fractions

5. You need pounds of fruits to make a

pudding. Sam has pounds of fruits. How

much more does he need to make the pudding?

A. lb C. lb

B. lb D. lb

Lesson Quiz for Student Response Systems

17

2419 24

17

3619

36

8 9

5 12