13. A rectangular box (no top) is welded together using sheet metal. The length of the box’s base is 18 in. longer than its width. The total surface area of the sheet metal that is used is 2,500 in.2.

(a) Using polynomials write an expression for the volume V in terms of x.

(b) Make a plot of V versus x for in.

(c) Determine the dimensions of the box that maximizes the volume and determine that volume.