Question 175046
Let l be the length of the rectangle

Let w be the width of the rectangle.

From the description of the problem we can write the following equations:

l=w-3  (Equation #1)

2l + 2w = 54 (Equation #2)

Substitute equation #1 into Equation #2 and simplifify

2*(w-3)+2*w=54

2w-6+2w = 54

4w = 60

Solve for w

w = 60/4 = 15

Substitute w = 15 into Equation #2 to solve for l

2*l + 2(15) = 54

2*l + 30 = 54

2*l = 54-30 = 24

l = 12

Also, w-l =15-12=3 (agrees with equation #1)

I hope that this helps.