calculus
posted by Sara .
A box with a square base and no top is to be made from a square piece of carboard by cutting 3 in. squares from each corner and folding up the sides. The box is to hold 7500 in3. How big a piece of cardboard is needed?
?in by ?in

Just like this one with slightly different numbers.
http://www.jiskha.com/display.cgi?id=1278659546