-20.2% is the change from 99 to 79
Calculation steps:
[( 79 - 99 ) ÷ 99] x 100 = -20.2%
Formula
Percentage change = [(79 - 99) / 99] x 100
Subtract the new number by the original number
79 - 99 = -20
-20 ÷ 99 = -0.20202020202020202
-0.20202020202020202 x 100 = -20.2%