Let w be the width
And let h be the length
h = w + 3
w * h = 28
w(w+3) = 28
w^2 + 3w = 28
Use a calculator (or use the quadratic formula) to get w=4
To find h, just add w by 3.
You get 7.
The dimensions of the rectangle is 4 by 7 cm.
Have an awesome day! :)