cardboard box 12 in wide, 18 in.long and 5 in. high. How many square inches of cardboard are used?
if we say that the box has 6 sides and no over-laps, then we know that:
top = bottom, 2(12x18) =432 sq inches
2xends, 2(12x5)=120 sq inches
2xsides, 2(18x5)=180 sq inches
total the surface areas =432+120+180=732 sq inches