-12.12% is the change from 990 to 870
Calculation steps:
[( 870 - 990 ) ÷ 990] x 100 = -12.12%
Formula
Percentage change = [(870 - 990) / 990] x 100
Subtract the new number by the original number
870 - 990 = -120
-120 ÷ 990 = -0.12121212121212122
-0.12121212121212122 x 100 = -12.12%