In this question it is already a given fact that Danielle is building a rectangular dog run. For solving this problem it is necessary to know the formula to find area of a rectangle. Once that information is known, then the problem becomes easy to solve. Width of the rectangular dog run built by Danielle = 8 feet Area of the rectangular dog run built by Danielle = 208 square feet We can assume the length of the rectangular dog run built by Danielle = L Now Area of the rectangular dog run = Width of the rectangular run * Length of the rectangular run 208 = 8 * L L = 208/8 = 26 feet So the length of the rectangular dog run built by Danielle is 26 feet.