-33.65% is the change from 639 to 424
Calculation steps:
[( 424 - 639 ) ÷ 639] x 100 = -33.65%
Formula
Percentage change = [(424 - 639) / 639] x 100
Subtract the new number by the original number
424 - 639 = -215
-215 ÷ 639 = -0.3364632237871675
-0.3364632237871675 x 100 = -33.65%