-74.4% is the change from 840 to 215
Calculation steps:
[( 215 - 840 ) ÷ 840] x 100 = -74.4%
Formula
Percentage change = [(215 - 840) / 840] x 100
Subtract the new number by the original number
215 - 840 = -625
-625 ÷ 840 = -0.7440476190476191
-0.7440476190476191 x 100 = -74.4%