Width is 14 ft, length is 28 ft
We know that the length is twice as long as the width. This can be represented by L=2W.
The equation to solve this is 84=W+W+L+L. We can replace both the L variables with 2W, since that is what L equals.
84=W+W+2W+2W. We simplifiy to get 84=6W. We divide 84 by 6 and get W=14.
Now that we know the width, finding the length is easier. L=2(14). L=28 ft.
To check our math we can do 28+28+14+14. 56+28=84 ft.
Therefore, the width is 14 ft and the length is 28 ft.