-50% is the change from 870 to 435
Calculation steps:
[( 435 - 870 ) ÷ 870] x 100 = -50%
Formula
Percentage change = [(435 - 870) / 870] x 100
Subtract the new number by the original number
435 - 870 = -435
-435 ÷ 870 = -0.5
-0.5 x 100 = -50%
Example