-20.1% is the change from 388 to 310
Calculation steps:
[( 310 - 388 ) ÷ 388] x 100 = -20.1%
Formula
Percentage change = [(310 - 388) / 388] x 100
Subtract the new number by the original number
310 - 388 = -78
-78 ÷ 388 = -0.20103092783505155
-0.20103092783505155 x 100 = -20.1%