What is the difference in surface areas, in square feet, of the two boxes?

Rectangular Prism: 3 ft by 4.5 ft by 2 ft

Cube: 3 ft

The difference is 3ft since the surface area for the prism is 57, and the surface area for the cube is 54.

You can use the surface area formula

2 (wl+hl+hw) = Area

2· (3·4.5+2·4.5+2·3) = 57

And a cubes surface area formula

6a^2 = Area

6·32=54