7th Grade Math

Examples 1–4 Add or subtract. Write in simplest form.

1. 1 75 + 8 71 2. 8 ^12 + 3 ^45 3. 7 65 - 3 ^16 4. 9 54 - 2 ^34

55 3 ^14 - 1 ^34 6. 5 ^23 - 2 ^35 7. 11 - 6 ^38 8. 16 - 5 ^56

Example 5 9. CARS A hybrid car’s gas tank can hold 11 _ 109 gallons of gasoline. It contains

8 _^34 gallons of gasoline. How much more gasoline is needed to fill the tank?

Find 8 - 3 _^34. Estimate 8 - 4 = 4

Using the denominator of the fraction in the subtrahend, 8 = 8 _^04.

Since _^04 is less than _^34 , rename 8 before subtracting.

8 7 _^4

4 Rename 8 as 7 +

_^4

4 or 7

_^4

4.

• 3 ^34 - 3 ^34 Subtract.

  ---

  
  

  4 41 Check for Reasonableness 4 ^14 ≈ 4 ✓

  
  

j. 11 52 - 2 ^35 k. 5 ^38 - 4 1211 l. 7 - 1 _^12

MEASUREMENT An urban

planner is designing a

skateboard park. What

will be the length

of the park and

the parking lot

combined?

120 _^1

2 +^40

_^1

3 =^120

_^3

6 +^40

_^2

6

= 160 + _^56

= 160 _^56

The total length is 160 _^56 feet.

m. MEASUREMENT Jermaine walked 1 _ 85 miles on Saturday and 2 _^12 miles

on Sunday. How many more miles did he walk on Sunday?

40 ft^13

120 ft^12

Subtrahend

The number to be

subtracted is called the

subtrahend.

Example:

8 – 4 = 4

subtrahend

154 Rational Numbers

139_156_C3L2_895130.indd 154 12/31/09 12:38 PM