-36.78% is the change from 870 to 550
Calculation steps:
[( 550 - 870 ) ÷ 870] x 100 = -36.78%
Formula
Percentage change = [(550 - 870) / 870] x 100
Subtract the new number by the original number
550 - 870 = -320
-320 ÷ 870 = -0.367816091954023
-0.367816091954023 x 100 = -36.78%