4-5 Inverse Operations

Addition*Remember inverse of addition and subtraction.

100

k+24.75 = 36.12

k = ?

k+24.75 = 36.12

  -24.75  = -24.75

k = 11.37

200

*Use your calculator, or think about how many 4ths make a whole. 

*Turn improper fractions into mixed numbers. Simplify fractions.

1/4+n = 5

n = ?

1/4+n = 5 (or 4 4/4)

-1/4    = -1/4

n = 4 3/4

300

4.08+m = 7

m = ?

4.08+m = 7

-4.08     = -4.08

m = 2.92

400

*How many 1/4 = 1/2? 

*Turn improper fractions into mixed numbers. Simplify fractions.

s+1/4 = 12 1/2

s = ?

s+1/4 = 12 1/2

  -1/4  = -1/4

s = 12 1/4

500

*Don't forget about your calculator!

*Turn improper fractions into mixed numbers. Simplify fractions.

2 2/3 + y = 4 1/4

y = ?

2 2/3 + y = 4 1/4

-2 2/3      = -2 2/3

y= 1 7/12

Subtraction*Remember inverse of addition and subtraction.

100

12.85 = x-4.34

x = ?

12.85 = x-4.34

+4.34 =  +4.34

x = 17.19

200

*Turn improper fractions into mixed numbers. Simplify fractions.

t-2/3 = 5/6

t = ?

t-2/3 = 5/6

 +2/3 = +2/3

t = 1 1/2

300

42.5 = v-23.45

v = ?

42.5 = v-23.45

+23.45 = +23.45

v = 65.95

400

n-0.005 = 0.8

n = ?

n-0.005 = 0.8

+0.005 = +0.005

n = 0.805

500

*Turn improper fractions into mixed numbers. Simplify fractions.

a-4 3/8 = 2 1/2

a = ?

a-4 3/8 = 2 1/2

+4 3/8 = +4 3/8

a = 6 7/8

Multiplication

100

*Remember RECIPRICAL 

1/2y = 10

y = ?

1/2y = 10

*2    = *2

y = 20

200

2.7s = 5.7

s = ?

2.7s = 5.7

÷2.7 = ÷2.7

s = 2.1

300

15.95 = 3.19n

n = ?

15.95 = 3.19n

÷3.19 = ÷3.19

n = 5

400

*Turn improper fractions into mixed numbers. Simplify fractions.

2/7q = 3

q = ?

2/7q = 3

*7/2 = *7/2

q = 10 1/2

500

*Turn improper fractions into mixed numbers. Simplify fractions.

7/10c = 4 1/5

c = ?

7/10c = 4 1/5

*10/7 = *10/7

c = 6

Division

100

*What do we multiply by to solve?

r/4 = 14

r = ?

r/4 = 14

*4  = *4

r = 56

200

*Round to the nearest hundredth.

72.67 = c ÷ 3.3

c = ?

72.67 = c ÷ 3.3

*3.3  =      *3.3

c = 239.81

300

x/4 = 2

x = ?

x/4 = 2

*4  = *4

x = 8

400

*Round to the nearest hundredth.

t÷5.4 = 9.01

t = ?

t÷5.4 = 9.01

 *5.4 = *5.4

t = 48.65

500

9 1/2 = k/9

k = ?

9 1/2 = k/9

*9     = *9

k = 85 1/2

Random

100

*Remember inverse of addition and subtraction.

a-4.6 = 1.2

a = ?

a-4.6 = 1.2

+4.6  = +4.6 

a = 5.8

200

*Remember inverse of addition and subtraction.

57+x = 144

x = ?

57+x = 144

-57    = -57

x = 87

300

c÷5 = 6

c = ?

c÷5 = 6

 *5  = *5

c = 30

400

49 = 7h

h = ?

49 = 7h

÷7 = ÷7

h = 7

500

m/7 = 12

m = ?

m/7 = 12

*7   = *7

m = 84