-22.31% is the change from 399 to 310
Calculation steps:
[( 310 - 399 ) ÷ 399] x 100 = -22.31%
Formula
Percentage change = [(310 - 399) / 399] x 100
Subtract the new number by the original number
310 - 399 = -89
-89 ÷ 399 = -0.22305764411027568
-0.22305764411027568 x 100 = -22.31%