-28.39% is the change from 391 to 280
Calculation steps:
[( 280 - 391 ) ÷ 391] x 100 = -28.39%
Formula
Percentage change = [(280 - 391) / 391] x 100
Subtract the new number by the original number
280 - 391 = -111
-111 ÷ 391 = -0.28388746803069054
-0.28388746803069054 x 100 = -28.39%