Answer:
591.5

Explanation:
Volume = length x width x height
Length = 13 ft. Because it is the same size has the height
Width = 7 ft.
Height = 13 ft.
13ft x 13ft x 7ft = 1,183 ft
BUT, that can't be the answer because we're solving a prism
So divide the volume.
1,183 divided by 2 equals 591.5