Part A.
The building is made up of two rectangular prism.
The left rectangular prism has base 8 ft by 12 ft and height 24 ft.
The right rectangular prism has base 32 ft by 12 ft and height 16 ft.
The volume of a rectangular prism is: V = LWH
For the building, the total volume is:
V = LWH + LWH
V = 8 ft * 12 ft * 24 ft + 32 ft * 12 ft * 16 ft
Part B.
V = 2304 ft^3 + 6144 ft^3
V = 8448 ft^3