-68.75% is the change from 128 to 40
Calculation steps:
[( 40 - 128 ) ÷ 128] x 100 = -68.75%
Formula
Percentage change = [(40 - 128) / 128] x 100
Subtract the new number by the original number
40 - 128 = -88
-88 ÷ 128 = -0.6875
-0.6875 x 100 = -68.75%