-2.86% is the change from 315 to 306
Calculation steps:
[( 306 - 315 ) ÷ 315] x 100 = -2.86%
Formula
Percentage change = [(306 - 315) / 315] x 100
Subtract the new number by the original number
306 - 315 = -9
-9 ÷ 315 = -0.02857142857142857
-0.02857142857142857 x 100 = -2.86%