-78.56% is the change from 639 to 137
Calculation steps:
[( 137 - 639 ) ÷ 639] x 100 = -78.56%
Formula
Percentage change = [(137 - 639) / 639] x 100
Subtract the new number by the original number
137 - 639 = -502
-502 ÷ 639 = -0.7856025039123631
-0.7856025039123631 x 100 = -78.56%