-50% is the change from 398 to 199
Calculation steps:
[( 199 - 398 ) ÷ 398] x 100 = -50%
Formula
Percentage change = [(199 - 398) / 398] x 100
Subtract the new number by the original number
199 - 398 = -199
-199 ÷ 398 = -0.5
-0.5 x 100 = -50%
Example