Find the surface area of the solid. round to the nearest whole unit, if necessary. a square pyramid with a base area of 9 ft² and a slant height of 8 ft.

To the risk of sounding redundant.

check the picture below, so, that's the pyramid, the base is a 3x3 and therefore has an area of 9 ft².

the slant height of the pyramid, is really the "altitude" or height of the triangular face, so each triangular face is just a triangle with a base of 3, and a height of 8.

Dwould be the answer