-3.73% is the change from 510 to 491
Calculation steps:
[( 491 - 510 ) ÷ 510] x 100 = -3.73%
Formula
Percentage change = [(491 - 510) / 510] x 100
Subtract the new number by the original number
491 - 510 = -19
-19 ÷ 510 = -0.03725490196078431
-0.03725490196078431 x 100 = -3.73%