-90.71% is the change from 420 to 39
Calculation steps:
[( 39 - 420 ) ÷ 420] x 100 = -90.71%
Formula
Percentage change = [(39 - 420) / 420] x 100
Subtract the new number by the original number
39 - 420 = -381
-381 ÷ 420 = -0.9071428571428571
-0.9071428571428571 x 100 = -90.71%