I think it is assumed that the table is a rectangle (hence "find the dimensions of the tabletop"). In that case, you have two equations: L*W=18 and 2L+2W=18, where, as you probably guessed, L and W are the length and width, respectively. Then you can take one of the equations, probably the second one, and get one of the variables by itself (ex: L=(18-2W)/2). Then plug this into the other equation (the one for area),so you should end up with something like W*(18-2W)/2. Once you multiply this out, you will end up with a quadratic equation. Solve it, ignore any negative values (b/c W is a width) and then plug the value for W into the perimeter equation to solve for L. Then you will have your dimensions.
