Linda has decided to grow her own vegetables and wants to fence off a rectangular garden. An adjacent building will serve as one side of the garden,
so she only needs to fence the other three sides. She wants the length to be
six feet longer than the width and she has enough material to build 18 feet of
fence. Use an algebraic expression to find the dimensions of the garden.
*Note: the shorter sides are the width, and the longer side is the length.