There is a formula to follow in solving for the area of a pentagon. However, since surface area is needed and dimensions of the wall is given, we only need to get the area of each wall and add them all up to get the surface area.
Pentagon has 5 sides or 5 walls. Each wall is 80ft by 18ft.
Area = 80 ft * 18 ft = 1440 ft²
Surface Area = 1440 ft² x 5 walls = 7,200 ft²