-19.29% is the change from 420 to 339
Calculation steps:
[( 339 - 420 ) ÷ 420] x 100 = -19.29%
Formula
Percentage change = [(339 - 420) / 420] x 100
Subtract the new number by the original number
339 - 420 = -81
-81 ÷ 420 = -0.19285714285714287
-0.19285714285714287 x 100 = -19.29%