39 square inches
You need the area of the square base
Area = side^2
A = 3 x 3 = 9
And the 4 triangle sides.
Area of a triangle = 1/2(base)(height)
a = 1/2 (3)(5) = 7.5
We have 4 of those triangles on this shape
4 x 7.5 = 30
Add the triangles to the base for goal surface area
30 + 9 = 39 square inches