-24.91% is the change from 851 to 639
Calculation steps:
[( 639 - 851 ) ÷ 851] x 100 = -24.91%
Formula
Percentage change = [(639 - 851) / 851] x 100
Subtract the new number by the original number
639 - 851 = -212
-212 ÷ 851 = -0.2491186839012926
-0.2491186839012926 x 100 = -24.91%