Question

The value of y varies directly with x. If x=25, then y=20.

a. Find the value of y when x=8.

b. Find the value of x when y=32.

Answer 1

a. y = 6.4

b. x = 40

Explanation:

y = kx

Find the proportionality constant, k:

20 = k(25)

k = 20/25 = 4/5 = 0.8

a. y = (0.8)(8) = 6.4

b. 32 = (0.8)x

x = 32/0.8 = 40