-19.52% is the change from 830 to 668
Calculation steps:
[( 668 - 830 ) ÷ 830] x 100 = -19.52%
Formula
Percentage change = [(668 - 830) / 830] x 100
Subtract the new number by the original number
668 - 830 = -162
-162 ÷ 830 = -0.19518072289156627
-0.19518072289156627 x 100 = -19.52%