Math dimensions

Question

if the length of a rectangular painting is 3 inches more then twice the width and has a perimeter of 84in what are the dimensions

Answer 1

Let "l" be the length and let "w" be the width.

The "length is 3 more then twice the width" means l = 3 + 2w

The perimeter of a rectangle is l + w + l + w = 2l + 2w and since the perimeter is 84 then 2l + 2w = 84

Substituting "3 + 2w" in place of "l" give us:

2(3 + 2w) + 2w = 84

6 + 4w + 2w = 84

6w = 78

w = 13

Since l = 3 + 2w then l = 3 + 2(13) = 29

So the rectangle is 13 inches by 29 inches

Answer 2

42 = L + W

42 = 2W + 3 + w

Can you solve for W and answer?