Question

If x varies directly with y and x=6 when y=8, find x when y=18.

Options:

13.5

12

24

12.5

Answer 1

x = 13.5

Explanation:

direct variation

y = kx

substitute x and y to find k

8 = k*6

divide by 6

8/6 =k

4/3 = k

y = 4/3 x

now put in y =18

18 = 4/3 x

multiply by 3/4

18 * 3/4 = 3/4 * 4/3 x

54/4 = x

change to a decimal

13.5 =x