-7.14% is the change from 840 to 780
Calculation steps:
[( 780 - 840 ) ÷ 840] x 100 = -7.14%
Formula
Percentage change = [(780 - 840) / 840] x 100
Subtract the new number by the original number
780 - 840 = -60
-60 ÷ 840 = -0.07142857142857142
-0.07142857142857142 x 100 = -7.14%