-83.59% is the change from 128 to 21
Calculation steps:
[( 21 - 128 ) ÷ 128] x 100 = -83.59%
Formula
Percentage change = [(21 - 128) / 128] x 100
Subtract the new number by the original number
21 - 128 = -107
-107 ÷ 128 = -0.8359375
-0.8359375 x 100 = -83.59%