Answer and explanation please

974 squared inches

to find surface you do as such here:

length x height x 2 [two because you have two of each side for this certain shape] (462)

width x height x 2 (336)

length x width x 2 (176)

then once you have all of them, you add them together and have your surface area! i’ll show how i solved the height x length for you :)

21 x 11 x2

231 x 2 = 462

hope this made sense!