-4.55% is the change from 879 to 839
Calculation steps:
[( 839 - 879 ) ÷ 879] x 100 = -4.55%
Formula
Percentage change = [(839 - 879) / 879] x 100
Subtract the new number by the original number
839 - 879 = -40
-40 ÷ 879 = -0.04550625711035267
-0.04550625711035267 x 100 = -4.55%