IF the cube is resting on the table in the normal way ... with two of its faces horizontal and the other four faces vertical, then any horizontal or vertical slice is a square.
You know what's fun ? Try doing this problem with cubes of chocolate cake, and after you make slices, look at them and then eat them.
The answer is 144ft^2 The formula of a trapezoid is a plus b over 2 then times height A and b are the bases which are 15 and 21 15+21 is 36 and divided by two is 18 18 times the height which is 8 And that gives u the answer