The perimeter of a tabletop is 28 ft the difference between 4 times the length and three times the width is 21 ft find the dimensions

Question

I need the dimensions of the tabletop

Answer 1

Let w = the width of the tabletop

Let L = the length of the tabletop

P = 2L + 2w

28 = 2L + 2w   (equation #1)

4L - 3w = 21   (equation #2)        Multiply eq. #1 by -2 and add to eq. #2.

  4L - 3w = 21

-4L - 4w = -56

       -7w = -35

          w = 5 feet

 4L - 3(5) = 21

4L - 15 = 21

4L = 36

L = 9 feet