-21.54% is the change from 390 to 306
Calculation steps:
[( 306 - 390 ) ÷ 390] x 100 = -21.54%
Formula
Percentage change = [(306 - 390) / 390] x 100
Subtract the new number by the original number
306 - 390 = -84
-84 ÷ 390 = -0.2153846153846154
-0.2153846153846154 x 100 = -21.54%