-31.2% is the change from 830 to 571
Calculation steps:
[( 571 - 830 ) ÷ 830] x 100 = -31.2%
Formula
Percentage change = [(571 - 830) / 830] x 100
Subtract the new number by the original number
571 - 830 = -259
-259 ÷ 830 = -0.31204819277108437
-0.31204819277108437 x 100 = -31.2%