Question 274107
Dear jpa:

You made the honest mistake of solving for a square instead of a rectangle.
If you make the width as X then the length has to be X+4 which would make the equation look like this

2x + 2(X+4) = 112 therefore
2X + 2X + 8 = 112 and then
     4X + 8 = 112 
         4X = 104
          X = 26

I hope this helps you