Graphing calculator aint' gon' help here. You're going to have to solve a quadratic equation, but you won't have the C coefficient to plug into the TI. Let's get started. Here's what we know: A = L x W L = W + 6 Let's substitute to get that pesky L out of there: A = (W + 6) x W A = (W^2) + 6W Well, shit. If it weren't for that squared term, we could've just solved here. Instead, it's time for... the QUADRATIC EQUATION WEEEEEEE!!!1!!!!1 (W^2) + 6W - A = 0 W = -6 + sqrt(36 + 4A)/2 Thankfully, we can simplify the radical. 4 is a factor we can pull out. Shall we? W = -6 + 2sqrt(9 + A)/2 Another step of simplification. 2 is a common factor. W = -3 + sqrt(9 + A) And we have our answer. B) sqrt(9 + A) - 3 Oops, forgot something. The quadratic formula has a +/- but I just put + so what gives? Well, for one, there are no negative answers in the choices. And, because of the context, that makes sense: you can't have a negative side length.