-87.48% is the change from 639 to 80
Calculation steps:
[( 80 - 639 ) ÷ 639] x 100 = -87.48%
Formula
Percentage change = [(80 - 639) / 639] x 100
Subtract the new number by the original number
80 - 639 = -559
-559 ÷ 639 = -0.8748043818466353
-0.8748043818466353 x 100 = -87.48%