The surface area is 624 inches squared.
Multiply 12 by 20 to get 240, then divide it by 2 to get 120 for the area of one triangular side.
Multiply 120 by 4 for the four triangular sides to get 480 inches squared.
Then multiply 12 by 12 for the base which will be 144 inches.
480 plus 144 equals 624 inches squared!
:D Goodluck on the rest of your homework or quiz!