-27.5% is the change from 840 to 609
Calculation steps:
[( 609 - 840 ) ÷ 840] x 100 = -27.5%
Formula
Percentage change = [(609 - 840) / 840] x 100
Subtract the new number by the original number
609 - 840 = -231
-231 ÷ 840 = -0.275
-0.275 x 100 = -27.5%