The length of a rectangle is twice its width. the perimeter of the rectangle is 24 inches. write a system of equations in 2 variables. use substitution to solve the problem

Let us assume the width of the rectangle = w
Let us assume the length of the rectangle = l
Then
l = 2w
Also 
Perimeter of the rectangle = 2 (l + w)
24 = 2 (2w + w)
24 = 2 (3w)
24 = 6w
w = 24/6
    = 4 inches
Now 
The length of the rectangle = 2w
                                            = 2 * 4 inches
                                            = 8 inches
So the length of the rectangle is 8 inches and the width is 4 inches.

The answer is e &