You wish to build a rectangular pen for your dog with 24 yards of fence. What are the dimensions (length and width) of the pen that will allow for maximum room to roam?

Is there a way to solve this question without using a graphing calculator or calculus?

Our teacher used a graphing calculator and found the maximum point to be (6,36) where the number 6 = the length and 36 = the width wirtten (L, W).

That's find and dandy but how does answer this question without a calculator and without calculus?