-83.65% is the change from 850 to 139
Calculation steps:
[( 139 - 850 ) ÷ 850] x 100 = -83.65%
Formula
Percentage change = [(139 - 850) / 850] x 100
Subtract the new number by the original number
139 - 850 = -711
-711 ÷ 850 = -0.8364705882352941
-0.8364705882352941 x 100 = -83.65%