-20% is the change from 660 to 528
Calculation steps:
[( 528 - 660 ) ÷ 660] x 100 = -20%
Formula
Percentage change = [(528 - 660) / 660] x 100
Subtract the new number by the original number
528 - 660 = -132
-132 ÷ 660 = -0.2
-0.2 x 100 = -20%
Example