-21.7% is the change from 857 to 671
Calculation steps:
[( 671 - 857 ) ÷ 857] x 100 = -21.7%
Formula
Percentage change = [(671 - 857) / 857] x 100
Subtract the new number by the original number
671 - 857 = -186
-186 ÷ 857 = -0.21703617269544925
-0.21703617269544925 x 100 = -21.7%