The length of a rectangle is four times its width. If the area of the rectangle is 100ft^2 find its perimeter

Let's first denote the width of the rectangle as x. Then the length of the rectangle would be 4x.

Since the formula for the area of a rectangle is length x width, we have:

Area = length x width
100 = 4x * x
100 = 4x^2

Now, we can solve for x:

4x^2 = 100
x^2 = 25
x = 5

Therefore, the width of the rectangle is 5ft and the length is 4(5) = 20ft.

To find the perimeter of the rectangle, we can use the formula for the perimeter of a rectangle:

Perimeter = 2(length + width)
Perimeter = 2(20 + 5)
Perimeter = 2(25)
Perimeter = 50ft

Therefore, the perimeter of the rectangle is 50ft.