Help this is a math sos!?

Question

a open box is to be constructed from a rectangular piece of cardboard which measures 18 inches by 20 inches to make the box a square shaped cut is made at each corner of the rectangle and the sides folded up. Each square cut must be a whole number of inches on each side determine what size cut will result in the box with the greatest volume? explain answer please so i understand!

Answer 1

Let C be the size of the cut. Then when you fold up the sides, you get a box whose

Height = C
Width = 18 - 2C
Length = 20 - 2C

Make a table with height, width, and length for every case where all three are positive, which will be for C = 1, 2, 3, 4, 5, 6, 7, or 8. Multiply them together to get volume. See which of the 8 answers is biggest.