-79.5% is the change from 639 to 131
Calculation steps:
[( 131 - 639 ) ÷ 639] x 100 = -79.5%
Formula
Percentage change = [(131 - 639) / 639] x 100
Subtract the new number by the original number
131 - 639 = -508
-508 ÷ 639 = -0.7949921752738655
-0.7949921752738655 x 100 = -79.5%