-78.57% is the change from 840 to 180
Calculation steps:
[( 180 - 840 ) ÷ 840] x 100 = -78.57%
Formula
Percentage change = [(180 - 840) / 840] x 100
Subtract the new number by the original number
180 - 840 = -660
-660 ÷ 840 = -0.7857142857142857
-0.7857142857142857 x 100 = -78.57%