-21.15% is the change from 870 to 686
Calculation steps:
[( 686 - 870 ) ÷ 870] x 100 = -21.15%
Formula
Percentage change = [(686 - 870) / 870] x 100
Subtract the new number by the original number
686 - 870 = -184
-184 ÷ 870 = -0.21149425287356322
-0.21149425287356322 x 100 = -21.15%