-21.57% is the change from 510 to 400
Calculation steps:
[( 400 - 510 ) ÷ 510] x 100 = -21.57%
Formula
Percentage change = [(400 - 510) / 510] x 100
Subtract the new number by the original number
400 - 510 = -110
-110 ÷ 510 = -0.21568627450980393
-0.21568627450980393 x 100 = -21.57%