Assume that the length is l and the width is w. Therefore, l is equal to 7 times its width (7*w) minus 28, or l=7*w-28. As we know that w*l = area = 9555, we can plug our value for l in to limit our equation to 1 variable, resulting in w*(7*w-28) = 9555. Adding 28 to both sides to separate the 7w (because we want to solve for that), we get 9583=7w. Then, to solve for the width, we can divide both sides by 7 to get that 9583/7=1369=w. Plugging that back into the formula that w*l=area, we get that 1369*l=9583 -- dividing 1369 from both sides to separate l, we get that l=7.
