-23.81% is the change from 420 to 320
Calculation steps:
[( 320 - 420 ) ÷ 420] x 100 = -23.81%
Formula
Percentage change = [(320 - 420) / 420] x 100
Subtract the new number by the original number
320 - 420 = -100
-100 ÷ 420 = -0.23809523809523808
-0.23809523809523808 x 100 = -23.81%