-91.9% is the change from 420 to 34
Calculation steps:
[( 34 - 420 ) ÷ 420] x 100 = -91.9%
Formula
Percentage change = [(34 - 420) / 420] x 100
Subtract the new number by the original number
34 - 420 = -386
-386 ÷ 420 = -0.919047619047619
-0.919047619047619 x 100 = -91.9%