what is the surface area of a pyramid if the length and width is 10 inches and the height is 9 inches?

Answer is 380 inches squared. The bottom side is 10x10 which is 100, then all 4 sides are 10x7 which is 70, but you have to multiply that by 4 so it becomes 280. Then you add 280 and 100, the final answer is 380in^2