Polynomial box question

Question

An open box that holds itself together can be made by cutting out a square of length x from each corner of a rectangular piece of cardboard, cutting on the solid line, and folding on the dashed lines, as shown below. Find a polynomial function V(x) that gives the volume of the resulting box if the original cardboard measures 30 cm by 40 cm. Sketch the graph of V(x) for x >0.

Answer 1

Draw and label a diagram!

V(x) = (30 - 2x)(40 - 2x)(x)