-19.31% is the change from 668 to 539
Calculation steps:
[( 539 - 668 ) ÷ 668] x 100 = -19.31%
Formula
Percentage change = [(539 - 668) / 668] x 100
Subtract the new number by the original number
539 - 668 = -129
-129 ÷ 668 = -0.19311377245508982
-0.19311377245508982 x 100 = -19.31%