-8.21% is the change from 840 to 771
Calculation steps:
[( 771 - 840 ) ÷ 840] x 100 = -8.21%
Formula
Percentage change = [(771 - 840) / 840] x 100
Subtract the new number by the original number
771 - 840 = -69
-69 ÷ 840 = -0.08214285714285714
-0.08214285714285714 x 100 = -8.21%