-10% is the change from 840 to 756
Calculation steps:
[( 756 - 840 ) ÷ 840] x 100 = -10%
Formula
Percentage change = [(756 - 840) / 840] x 100
Subtract the new number by the original number
756 - 840 = -84
-84 ÷ 840 = -0.1
-0.1 x 100 = -10%
Example