Answer:

1. 80

2. 27

3. 12

Step-by-step explanation:

1. 4/10 = 32/N

10 x 32 = 4 x N

320 = 4N

N = 320/4

N = 80

2. N/3 = 90/10

N/3 = 9/1 or 9

N = 3 x 9

N = 27

3. 15/5 = N/4

3/1 or 3 = N/4

3 x 4 = N

N = 12