Question

y varies directly with x. When y = 12, x = 16. Find x when y = 24.

Answer 1

y = 12
when
x = 16
thus we have the point

(16,12)
and we have the point
(x, 24)

x/16 = 24/12
x = 24(16)/12
x = 32

Answer 2

I just used a ratio

x2/x1 = y2/y1

Answer 3

since they change proportionally the two ratios are equal