-97.75% is the change from 400 to 9
Calculation steps:
[( 9 - 400 ) ÷ 400] x 100 = -97.75%
Formula
Percentage change = [(9 - 400) / 400] x 100
Subtract the new number by the original number
9 - 400 = -391
-391 ÷ 400 = -0.9775
-0.9775 x 100 = -97.75%
Example