-17.07% is the change from 615 to 510
Calculation steps:
[( 510 - 615 ) ÷ 615] x 100 = -17.07%
Formula
Percentage change = [(510 - 615) / 615] x 100
Subtract the new number by the original number
510 - 615 = -105
-105 ÷ 615 = -0.17073170731707318
-0.17073170731707318 x 100 = -17.07%