Question

The length of a rectangle is 4 inches more than its width, and its perimeter is 36 inches. Find the width of the rectangle.

Answer 1

perimeter is the distance around the rectangle, which would be l + w + l + w, or 2l + 2w. So now you have 2 equations:

1. l = w + 4 (length is 4 inches more than width)
2. 2l + 2w = 36 (perimeter is 36 inches)

you can substitute "w + 4" for "l" in the second equation, because the first equation tells us they are equal:

2(w + 4) + 2w = 36
2w + 8 + 2w = 36
4w + 8 = 36
4w = 28
w = 7

Then substitute 7 for w in equation 1:

l = 7 + 4
l = 11

Then check that we got the right answer.

l = w + 4
11 = 7 + 4
11 = 11 (check!)

2l + 2w = 36
2(11) + 2(7) = 36
22 + 14 = 36
36 = 36 (check!)