-21.43% is the change from 420 to 330
Calculation steps:
[( 330 - 420 ) ÷ 420] x 100 = -21.43%
Formula
Percentage change = [(330 - 420) / 420] x 100
Subtract the new number by the original number
330 - 420 = -90
-90 ÷ 420 = -0.21428571428571427
-0.21428571428571427 x 100 = -21.43%