-42.86% is the change from 420 to 240
Calculation steps:
[( 240 - 420 ) ÷ 420] x 100 = -42.86%
Formula
Percentage change = [(240 - 420) / 420] x 100
Subtract the new number by the original number
240 - 420 = -180
-180 ÷ 420 = -0.42857142857142855
-0.42857142857142855 x 100 = -42.86%