Question

Equal squares of side length x are removed from each corner of a 20 inch by 30 inch piece of cardboard, and the sides are turned up to form a box with no top. Write the volume V of the box as a function of x.

Answer 1

V = x (30-2x)(20-2x)
multiply that out

Of course part 2 will be to take the derivative and set it to zero to find the height for maximum volume.