On increasing the length of a rectangle by 20% and decreasing its breadth by 20%, what is the change in its area?
Let the length be l
And, breadth be b
Now,
Area = l × b = lb
Increase in length = 20% of length + length
Decrease in breadth = breadth - 20% of breadth
Since,
Therefore,
The area is decreased
= 4%
Hence change in area = 4% decrease