Question

The formula for the perimeter of a rectangle is P = 2L + 2W. The length of a rectangle is 3 times its width. Which expression represents the perimeter of the rectangle?

Answer 1

The perimeter of a rectangle is given by the following formula:     P = 2W + 2L

To solve this formula for W, the goal is to isolate this variable to one side of the equation such that the width of the rectangle (W) can be solved when given its perimeter (P) and length (L).

     P = 2W + 2L

          subtract 2L from both sides of the equation

     P - 2L = 2W + 2L - 2L

     P - 2L = 2W

           divide both sides of the equation by 2

     (P - 2L)/2 = (2W)/2

     (P - 2L)/2 = (2/2)W

     (P - 2L)/2 = (1)W

     (P - 2L)/2 = W

Thus, given that the perimeter (P) of a rectangle is defined by    P = 2W + 2L ,

   then its width (W) is given by    W = (P - 2L)/2