The volume of a box with a square base (as in the figure below) is $\displaystyle{{s}}^{{2}}{h}\usepackage{cmbright}\Huge\$ cubic inches, where s is the length of each side of the base and h is the height of the box.

If a box has height 20 inches and volume 4500 cubic inches, what is the length (in inches) of each side of the base?