Let us set up some variables:
Now let us set up some equations based on the facts:
- length of rectangle is 4 times its width --> L = 4W
- perimeter of rectangle is 80 --> 2L + 2W = 80
Equations:
L = 4W -- equation 1
2L + 2W = 80 -- equation 2
Plug the value of L from equation 1 into equation 2
2(4W) + 2W = 80
8W + 2W = 80
10W = 80
W = 8 -- equation 3
Plug the value of W from equation 3 into equation 1:
L = 4W = 4 * 8 = 32
Therefore the length is 32 and the width is 8.
Hope that helps!