-19.41% is the change from 639 to 515
Calculation steps:
[( 515 - 639 ) ÷ 639] x 100 = -19.41%
Formula
Percentage change = [(515 - 639) / 639] x 100
Subtract the new number by the original number
515 - 639 = -124
-124 ÷ 639 = -0.19405320813771518
-0.19405320813771518 x 100 = -19.41%