The perimeter of a rectangle is 140 feet. the length of the rectangle is 6 more than 2 times the width. what is the length of the rectangle?

The equations we get are
l = 6 + 2w (We get this from "The length of the rectangle is 6 more than 2 times the width.")
and
2l + 2w = 140 (We get this from the perimeter. Two times the length plus two times the width equals the perimeter of a quadrilateral.)

The first equation can be written as
l - 2w = 6

So now we have
2l + 2w = 140
l - 2w = 6
____________
Add the two equations.
We get 3l = 146

Divide by 3 on both sides.
l = 48

Your answer is 48.