-80% is the change from 155 to 31
Calculation steps:
[( 31 - 155 ) ÷ 155] x 100 = -80%
Formula
Percentage change = [(31 - 155) / 155] x 100
Subtract the new number by the original number
31 - 155 = -124
-124 ÷ 155 = -0.8
-0.8 x 100 = -80%
Example