-30.87% is the change from 311 to 215
Calculation steps:
[( 215 - 311 ) ÷ 311] x 100 = -30.87%
Formula
Percentage change = [(215 - 311) / 311] x 100
Subtract the new number by the original number
215 - 311 = -96
-96 ÷ 311 = -0.3086816720257235
-0.3086816720257235 x 100 = -30.87%