The area of a rectangle remains unchanged when it is made 5cm shorter and 5cm wider or when it is made 2cm longer and 1cm narrower. Its area, in square cm, is:
LW = (L+5)*(W-5)
LW = LW + 5W -5L -25
5L - 5W = 25
(L +2)(W-1) = L W
-L + 2W = 2
-5L +10W = 10
Combining equations 3 and 6,
5W = 35
W = 7
L = 2W-2 = 12
Area = 84 cm^2