the question reads:

A box with a square base and open top must have a volume of 32,000 cm^3 . Find the dimensions of the box that minimize the amount of material used.

Now I know the general method, I'm just not sure how to set it up. so far I've come up with the equation:

32,000=y*x (y*x means y times x)

I've been trying to think up a second equation to find the dimensions but it's just not coming to me. Any thoughts?