The radius of a circle has been reduced from 9 cm to 7 cm . the appropriate percentage decrease in area is?

Original area = (22/7) x 9 x 9 cm²
New area = (22/7) x 7 x 7 cm²
∴ Decrease = 22/7 x [(9)² -(7)²] cm²
=(22/7) x 16 x 2 cm²
Decrease percent = [(22/7 x 16 x 2) /( 7/22 x 9 x 9)] x 100 %
= 39.5 %