-38.03% is the change from 831 to 515
Calculation steps:
[( 515 - 831 ) ÷ 831] x 100 = -38.03%
Formula
Percentage change = [(515 - 831) / 831] x 100
Subtract the new number by the original number
515 - 831 = -316
-316 ÷ 831 = -0.3802647412755716
-0.3802647412755716 x 100 = -38.03%