#### Answer

640 $ft^{3}$

#### Work Step by Step

We have to consider the pentagonal prism as composed by a triangular prism and a parallelepiped
Volume = Volume of the triangular prism + Volume of the parallelepiped
Volume = $\frac{8 ft \times 2 ft \times 10 ft }{2}$ + (8 ft $\times$ 7 ft $\times$ 10 ft)
Volume = 640 $ft^{3}$