A farmer wants to increase the area of his rectangular pen but keep the pen a rectangular shape. He decides to add 2 1/2 feet of fencing to the width of the pen, but the length will remain 9 1/4 feet. The new area will be 108 3/4 square feet. Which equation can be used to determine the original width, w, of the pen?

9 1/4(w+2 1/2)=108 3/4

9 1/4w+2 1/2=108 3/4

2 1/2(w+9 1/4)=108 3/4

2 1/2w+9 1/4=108 3/4