-50.15% is the change from 680 to 339
Calculation steps:
[( 339 - 680 ) ÷ 680] x 100 = -50.15%
Formula
Percentage change = [(339 - 680) / 680] x 100
Subtract the new number by the original number
339 - 680 = -341
-341 ÷ 680 = -0.5014705882352941
-0.5014705882352941 x 100 = -50.15%