-21.88% is the change from 128 to 100
Calculation steps:
[( 100 - 128 ) ÷ 128] x 100 = -21.88%
Formula
Percentage change = [(100 - 128) / 128] x 100
Subtract the new number by the original number
100 - 128 = -28
-28 ÷ 128 = -0.21875
-0.21875 x 100 = -21.88%