Answer:
x = 50
Explanation:
Given that y varies directly as x then the equation relating them is
y = kx ← k is the constant of variation
To find k use the condition
x = 10 when y = 40, then
40 = 10k ( divide both sides by 4 )
4 = k
y = 4x ← equation of variation
When y = 200, then
200 = 4x ( divide both sides by 4 )
50 = x