What is the surface area

I believe it is 144. To find the surface area of a shape I need to find the area of all the sides. So first u need to find the area of the rectangle 5 by 8. Multiply them together to get 40. Then multiply the 40 by 3 since there are 3 rectangles in the shape that measure the same. You’d get 120 from that. Then u need to find the area of the triangle. So multiply the 4x6 to get 24 then also multiply is by 1/2 to get 12. Then multiply the 12 by 2 since there are two triangles. So then u add them up to get 144.
Hope this helped and plz inform me if it’s wrong.