-93.33% is the change from 315 to 21
Calculation steps:
[( 21 - 315 ) ÷ 315] x 100 = -93.33%
Formula
Percentage change = [(21 - 315) / 315] x 100
Subtract the new number by the original number
21 - 315 = -294
-294 ÷ 315 = -0.9333333333333333
-0.9333333333333333 x 100 = -93.33%