-25.26% is the change from 855 to 639
Calculation steps:
[( 639 - 855 ) ÷ 855] x 100 = -25.26%
Formula
Percentage change = [(639 - 855) / 855] x 100
Subtract the new number by the original number
639 - 855 = -216
-216 ÷ 855 = -0.25263157894736843
-0.25263157894736843 x 100 = -25.26%