Just simplify the given equation
y = 7.2 + 4(x-2)
y = 7.2 + 4x - 8
y = 4x - 0.8
Now they want to know the answer if X = 2
y = 4(2) - 0.8
y = 8 - 0.8
y = 7.2
For cylinders to be similar, the ratio between their height and radius must be equal.Our cylinder's ratio is :

The only cylinder with same ratio is the one at the choice B.
I
2/5 of 2.5. = 2x2.5 / 5x1 = 5/5 = 1 pound