Treavor, draw a picture and label the info given. If your width is w, then your length is 2w, right?
How do you find area? l x w. Then we have that 2w x w = 115200, or 2w2 = 115200.
Divide both sides by two. w2 = 57600
Then take the square root of both sides and get that w = 240 ft.