-83.25% is the change from 830 to 139
Calculation steps:
[( 139 - 830 ) ÷ 830] x 100 = -83.25%
Formula
Percentage change = [(139 - 830) / 830] x 100
Subtract the new number by the original number
139 - 830 = -691
-691 ÷ 830 = -0.8325301204819278
-0.8325301204819278 x 100 = -83.25%