The lateral surface area is the surface area of the cube excluding the base and the top, which would make 4 square planes.
First we can find the area of a square plane:
4 1/2 x 4 1//2
=20 1/4 ft²
We can then multiply the area of plane by 4:
20 1/4 x 4
=81 ft²
Therefore the answer is 81 ft².
Hope it helps!
