find an answer for this the length of a rectangle is 4 times the width. the perimeter of the rectangle is 80cm, find the length of each side

Let L = 4W

Then 2(4W) + 2W = 80

Then 10W = 80   and W = 8

And L = 4(8) = 32.

Since the length is four times the width, width is written as L/4.

To find the perimeter you need 2L + 2W=80

So with the given information, your equation should look like:

2(L/4) + 2L = 80