-30.21% is the change from 331 to 231
Calculation steps:
[( 231 - 331 ) ÷ 331] x 100 = -30.21%
Formula
Percentage change = [(231 - 331) / 331] x 100
Subtract the new number by the original number
231 - 331 = -100
-100 ÷ 331 = -0.3021148036253776
-0.3021148036253776 x 100 = -30.21%