-18.08% is the change from 780 to 639
Calculation steps:
[( 639 - 780 ) ÷ 780] x 100 = -18.08%
Formula
Percentage change = [(639 - 780) / 780] x 100
Subtract the new number by the original number
639 - 780 = -141
-141 ÷ 780 = -0.18076923076923077
-0.18076923076923077 x 100 = -18.08%