Let x be the length of the rectangle, then its width is x-2.
The area of a rectangle is L x W OR x.(x-2). Expand it = x² - 2x = AREA.
Or x² - x = 168
x²-2x-168 = 0. This is a quadratic equation to solve for x:
x' = [-b+√(b²-4ac)]/2a and x" = [-b-√(b²-4ac)]/2a
you will find x' =14 and x" = -12 (extraneous value not to be considered), so
x=14
