-79.49% is the change from 390 to 80
Calculation steps:
[( 80 - 390 ) ÷ 390] x 100 = -79.49%
Formula
Percentage change = [(80 - 390) / 390] x 100
Subtract the new number by the original number
80 - 390 = -310
-310 ÷ 390 = -0.7948717948717948
-0.7948717948717948 x 100 = -79.49%