-97.06% is the change from 510 to 15
Calculation steps:
[( 15 - 510 ) ÷ 510] x 100 = -97.06%
Formula
Percentage change = [(15 - 510) / 510] x 100
Subtract the new number by the original number
15 - 510 = -495
-495 ÷ 510 = -0.9705882352941176
-0.9705882352941176 x 100 = -97.06%