The volume of a prism is given by the product of its base area and its height. Since the two heights are the same, let's look at the bases.
The first prism has a rectangle for base, with sides 4 and 20 inches. This means that its area is
squared inches.
The second prism has a right triangle for base, with legs 16 and 10 inches. This means that its area is
squared inches.
So, both prisms have the same height and the same base area. This means that they have the same volume as well, since in both cases it is given by
inches cubed.