math
posted by Mary .
The area of a rectangle is 84 square units. If its length is shortened by 7 units and its width by 2 units a square is formed. Determine the area of the square.

Let s be the square.
lw=84
(l7)=s=(w2)
l= w+5
(w+5)w=84
multiply that out, solve for w (it is a quadratic).