-39.22% is the change from 510 to 310
Calculation steps:
[( 310 - 510 ) ÷ 510] x 100 = -39.22%
Formula
Percentage change = [(310 - 510) / 510] x 100
Subtract the new number by the original number
310 - 510 = -200
-200 ÷ 510 = -0.39215686274509803
-0.39215686274509803 x 100 = -39.22%