-27.32% is the change from 421 to 306
Calculation steps:
[( 306 - 421 ) ÷ 421] x 100 = -27.32%
Formula
Percentage change = [(306 - 421) / 421] x 100
Subtract the new number by the original number
306 - 421 = -115
-115 ÷ 421 = -0.27315914489311166
-0.27315914489311166 x 100 = -27.32%