Arectangular prism has a height of 4 inches and a width of 12 inches. if the prism can hold 432 cubic inches of water, what is the height of the prism?

Given,

Height of the rectangular prism (h) = 4 inches
Width of the rectangular prism (w) = 12 inches
Since the prism can hold 432 cubic inches of water, 
Volume of the rectangular prism (V) = 432 inches³

Formula for Volume of a rectangular prism (V) is,

V = whl

I am assuming you are looking for the third side, the length (l) of the prism.

From the above formula for volume, 

Length of the prism (l) = V ÷ wh = 432 ÷ (4x12) = 432 ÷ 48 = 9 inches