Answer is C but can't figure it out.

C. 2,940 ft³

Step-by-step explanation:

The building is composed of a triangular prism and a rectangular prism

Therefore,

Volume of air in the building = volume of the triangular prism + volume of the rectangular prism

Volume of triangular prism = ½*bhl

b = 4 yards = 4*3 = 12 ft

h = 15 - 9½ = 5½ = 5.5 ft

l = 20 ft

Volume of triangular prism = ½*12*5.5*20 = 660 ft³

Volume of rectangular prism = W*H*L

W = 4 yds = 12 ft

H = 9½ = 9.5

L = 20 ft

Volume of rectangular prism = 12*9.5*20 = 2,280 ft³

✔️Volume of air in the building = 660 + 2,280 = 2,940 ft³

b

step-by-step explanation:

10000

step-by-step explanation: divide by 2,