-8.61% is the change from 639 to 584
Calculation steps:
[( 584 - 639 ) ÷ 639] x 100 = -8.61%
Formula
Percentage change = [(584 - 639) / 639] x 100
Subtract the new number by the original number
584 - 639 = -55
-55 ÷ 639 = -0.08607198748043818
-0.08607198748043818 x 100 = -8.61%