Answer:
In this rectangular prism, opposite sides are equal.
So if we find the 3 different sides, we would need to multiply those individual sides by 2 (because opposite sides are equal/have the same area) and then add them to get the surface area.
One side (the front and back side);
The width is 8 and the height is 7, so (8 x 7) = 56. Though, it's opposite side is the same as well so we multiply 56 by 2, (56 x 2) = 112
Second side (the left and right side);
The width is 18 and the height is 7, so (18 x 7) = 126. Though, it's opposite side is also the same as well, so we multiply 126 by 2, (126 x 2) = 252
Third side (the top and bottom side);
The width is 8 and the height is 18, so (8 x 18) = 144. Though, it's opposite side is also the same as well, so we multiply 144 by 2, (144 x 2) = 288
Now, we add all the areas we've gathered:-
112 + 252 + 288 = 652 square cm