-55.17% is the change from 870 to 390
Calculation steps:
[( 390 - 870 ) ÷ 870] x 100 = -55.17%
Formula
Percentage change = [(390 - 870) / 870] x 100
Subtract the new number by the original number
390 - 870 = -480
-480 ÷ 870 = -0.5517241379310345
-0.5517241379310345 x 100 = -55.17%