-80% is the change from 840 to 168
Calculation steps:
[( 168 - 840 ) ÷ 840] x 100 = -80%
Formula
Percentage change = [(168 - 840) / 840] x 100
Subtract the new number by the original number
168 - 840 = -672
-672 ÷ 840 = -0.8
-0.8 x 100 = -80%
Example