Question

The variable y is directly proportional to the variable x. If y = 9 when x = 5, what is the value of y when x = 20?

Answer 1

y=36

Explanation:

36

y = kx

9 = 5k

9

5

= k

y =

9

5

(20)

y = 36

Answer 2

y = 36

Explanation:

so there directly proportional..so lets make a proportion

if y = 9 when x = 5, what is the value of y when x = 20...

5 20

------ = ----- (cross multiply)

9 y

(5)(y) = (20)(9)

5y = 180

y = 180/5

y = 36 <=== so when x = 20, y = 36