-80.81% is the change from 99 to 19
Calculation steps:
[( 19 - 99 ) ÷ 99] x 100 = -80.81%
Formula
Percentage change = [(19 - 99) / 99] x 100
Subtract the new number by the original number
19 - 99 = -80
-80 ÷ 99 = -0.8080808080808081
-0.8080808080808081 x 100 = -80.81%