Step-by-step explanation:
such a rectangular prism is in that sense like a cube (or die) : it has 6 sides or surface areas. top, down, front, back, left, right.
to get the total surface area we need to calculate each individual side area and sum all 6 of them up.
since it is a rectangular shape, there are 3 pairs of equal side areas, so, we really need to calculate only 3 different ones :
front and back : each is
10×9 = 90 in², both together are 180 in²
left and right : each is
8×9 = 72 in², both together are 144 in²
top and bottom : each is
10×8 = 80 in², both together are 160 in²
the total surface area of the prism is
180 + 144 + 160 = 484 in²
