Each edge of a right triangular prism is 8 inches in length. what is the surface area of the right triangular prism?

Check the picture below.

since each edge is 8 inches, that simply means the right-triangle has a base of 8 and a height/altitude of 8 as well.

and since the triangular prism is really just two triangles and 3 rectangles, as you see there, we can simply get the area of each figure and sum them up, and that's the surface area of the prism.