What function expresses the volume of the box in terms of the side of the squares cut out?

Question

A 5-sided, open topped box is to be formed from a rectangular piece of cardboard that is 28 inches by 15 inches. Congruent squares are to be cut from each corner and the resulting flaps will be folded up to form the box.

Answer 1

V = height x width x length = X(28-2X)(15-2X) where X is the side of the squares cut out