-53.01% is the change from 830 to 390
Calculation steps:
[( 390 - 830 ) ÷ 830] x 100 = -53.01%
Formula
Percentage change = [(390 - 830) / 830] x 100
Subtract the new number by the original number
390 - 830 = -440
-440 ÷ 830 = -0.5301204819277109
-0.5301204819277109 x 100 = -53.01%