If we were to fold this into a prism, the rectangle on the left would be the base. The short sides of the triangles would fold to meet up with the 5 inch sides of the base. Then the rectangle on the right would fold down and fit between the two triangles, meeting up with the base. Visualizing the shape in 3 dimensions allows us to figure out the lengths of some sides. For example, the short sides of the triangles both equal 5 inches. Also, the long sides of the triangles equal 13 inches and the long side of the base is 8 inches.
The surface area is the area of all the surfaces.
8*5=40
8*12=96
2*(0.5*5*12)=60
13*8=104
Add these up..
40+96+60+104=300 in^2
