Answer:
x = 9
Explanation:
Given y varies directly with x then the equation relating them is
y = kx ← k is the constant of variation
To find k use the given condition when y = 16, x = 4
16 = 4k ( divide both sides by 4 )
k = 4
y = 4x ← equation of variation
When y = 36, then
36 = 4x ( divide both sides by 4 )
x = 9