-50.2% is the change from 510 to 254
Calculation steps:
[( 254 - 510 ) ÷ 510] x 100 = -50.2%
Formula
Percentage change = [(254 - 510) / 510] x 100
Subtract the new number by the original number
254 - 510 = -256
-256 ÷ 510 = -0.5019607843137255
-0.5019607843137255 x 100 = -50.2%