Sarah has a new puppy and she wants to maximize her outdoor time, so she builds her a fenced in play area. She has 40 feet of fencing, and she wants to fence off a rectangular area next to her house. The house will be one side of the play area, so that side needs no fencing. In order for the puppy to have adequate space, the area needs to be at least 5 feet long and5 feet wide. What is the largest area she could have? Is there a smallest area she could have if she wants to use all 40 feet of fencing?