2011 AMC 10B Problem 14

Let the side lengths be $l,w.$ We wish to find $2(l+w).$ From the Pythagorean Theorem, we get $$25 = \sqrt{l^2+w^2}$$$$l^2+w^2 = 625$$ We also know $lw = 168.$ As such $$\begin{aligned}l^2+2lw+ w^2 &= (l+w)^2 \\&= 961 \\&= 31^2.\end{aligned}$$ This makes $l+w = 31,$ and as such, our answer is $31\cdot 2=62.$ Thus, the correct answer is C .