-39.44% is the change from 639 to 387
Calculation steps:
[( 387 - 639 ) ÷ 639] x 100 = -39.44%
Formula
Percentage change = [(387 - 639) / 639] x 100
Subtract the new number by the original number
387 - 639 = -252
-252 ÷ 639 = -0.39436619718309857
-0.39436619718309857 x 100 = -39.44%