If the length of a rectangle is increased by 20% and its breadth is decreased by 20%, then its area:-

increases by 4% decreases by 4% decreases by 1% remains unchanged

decreases by 4%

Actual :   New L →         5     :      6      (inc. by 20%) B →         5     :      4      (dec. by 20%) Area ⇒   25    :    24   ⇒ -1 (decreased) So, decreased % = \(\frac{1}{25}\) = 4%