Faye has 20 ft of fencing to make a rectangular pen for her dog.What is the largest area that she can fence in?

faye has 20feet of fencing to make a rectangular pen for her dog. What is the the largest area that she can fence in?|||A square is a special rectangle in which all the sides are congruent, with that said the largest area would be a 5x5 square totaling 25 square foot area, other wise it goes to 6x4 then 7x3, 8x2 and lastly 9x1 and none of those have an area larger than 25 square feet