-19.4% is the change from 830 to 669
Calculation steps:
[( 669 - 830 ) ÷ 830] x 100 = -19.4%
Formula
Percentage change = [(669 - 830) / 830] x 100
Subtract the new number by the original number
669 - 830 = -161
-161 ÷ 830 = -0.19397590361445782
-0.19397590361445782 x 100 = -19.4%