-55% is the change from 220 to 99
Calculation steps:
[( 99 - 220 ) ÷ 220] x 100 = -55%
Formula
Percentage change = [(99 - 220) / 220] x 100
Subtract the new number by the original number
99 - 220 = -121
-121 ÷ 220 = -0.55
-0.55 x 100 = -55%
Example