Let both length and breadth of the rectangle be l=10 cm and b=10 cm Area of rectangle = A=l×b=10×10=100cm2 New length when it is increased by 10% = l′=10+(
10
100
×10)=11 cm Similarly, new breadth when it is increased by 20% = b′=10+(
20
100
×10)=12cm ⇒ New area = A′=11×12=132cm2 ∴ % increase =