-23.1% is the change from 870 to 669
Calculation steps:
[( 669 - 870 ) ÷ 870] x 100 = -23.1%
Formula
Percentage change = [(669 - 870) / 870] x 100
Subtract the new number by the original number
669 - 870 = -201
-201 ÷ 870 = -0.23103448275862068
-0.23103448275862068 x 100 = -23.1%