-57.5% is the change from 80 to 34
Calculation steps:
[( 34 - 80 ) ÷ 80] x 100 = -57.5%
Formula
Percentage change = [(34 - 80) / 80] x 100
Subtract the new number by the original number
34 - 80 = -46
-46 ÷ 80 = -0.575
-0.575 x 100 = -57.5%
Example