-17.4% is the change from 339 to 280
Calculation steps:
[( 280 - 339 ) ÷ 339] x 100 = -17.4%
Formula
Percentage change = [(280 - 339) / 339] x 100
Subtract the new number by the original number
280 - 339 = -59
-59 ÷ 339 = -0.17404129793510326
-0.17404129793510326 x 100 = -17.4%