Step-by-step explanation:
y = kx, where k is a real constant.
When y = 12, x = 5.
=> (12) = (5)k, k = 2.4.
Therefore when y = 30,
x = y/k = (30)/(2.4) = 12.5.
The answer is 12.5.
There's nothing preventing us from computing one integral at a time:



Expand the integrand completely:

Then
