-16.16% is the change from 990 to 830
Calculation steps:
[( 830 - 990 ) ÷ 990] x 100 = -16.16%
Formula
Percentage change = [(830 - 990) / 990] x 100
Subtract the new number by the original number
830 - 990 = -160
-160 ÷ 990 = -0.16161616161616163
-0.16161616161616163 x 100 = -16.16%