-50.75% is the change from 668 to 329
Calculation steps:
[( 329 - 668 ) ÷ 668] x 100 = -50.75%
Formula
Percentage change = [(329 - 668) / 668] x 100
Subtract the new number by the original number
329 - 668 = -339
-339 ÷ 668 = -0.5074850299401198
-0.5074850299401198 x 100 = -50.75%