Joe will build a rectangular pen for his dog. a wall will form one side of the pen. joe has 40 ft of fencing to form the other three sides. joe plans to build the pen so that it has its maximum possible area. what will be the dimensions of joe’s dog pen?

The length would be 16 ft on both sides.. The width would be 7 ft, I think since a wall is forming one side, and he 40 ft, so in order to make the other three side the maximum would be 39 ft, so I think you get it now. This is just my guess... I'm only in sixth grade :/