-9.08% is the change from 870 to 791
Calculation steps:
[( 791 - 870 ) ÷ 870] x 100 = -9.08%
Formula
Percentage change = [(791 - 870) / 870] x 100
Subtract the new number by the original number
791 - 870 = -79
-79 ÷ 870 = -0.09080459770114943
-0.09080459770114943 x 100 = -9.08%