Surface area will consist of:
2 triangles, 3 rectangles:
Solving for triangles:
A=1/2bh
A=1/2(120)
A=60
60*2 gives us the surface area of both triangular sides.
Solve for rectangles:
(17*20)+(8*20)+(15*20)
(340)+(160)+(300)
(800)
800+120=920
The surface area of the prism is 920 square feet