-9.78% is the change from 920 to 830
Calculation steps:
[( 830 - 920 ) ÷ 920] x 100 = -9.78%
Formula
Percentage change = [(830 - 920) / 920] x 100
Subtract the new number by the original number
830 - 920 = -90
-90 ÷ 920 = -0.09782608695652174
-0.09782608695652174 x 100 = -9.78%