Victoria G. answered • 10/23/16

Tutor

New to Wyzant
Loves math - loves helping others learn math

First you should consider the formulas for the Perimeter of a rectangle.

P = 2W + 2L

Then you should consider the information that is given to you in the problem.

W = L - 13

and

P = 90

Now, bring them together:

P = 2W + 2L

P = 2(L - 13) + 2L

Substitute in numbers and start crunching:

90 = 2(L - 13) + 2L

90 = 2L - 26 + 2L = 4L -26

add 26 to both sides

90 + 26 = 4L

116 = 4L

Divide by 4

29 = L