-28.91% is the change from 128 to 91
Calculation steps:
[( 91 - 128 ) ÷ 128] x 100 = -28.91%
Formula
Percentage change = [(91 - 128) / 128] x 100
Subtract the new number by the original number
91 - 128 = -37
-37 ÷ 128 = -0.2890625
-0.2890625 x 100 = -28.91%