-20.79% is the change from 505 to 400
Calculation steps:
[( 400 - 505 ) ÷ 505] x 100 = -20.79%
Formula
Percentage change = [(400 - 505) / 505] x 100
Subtract the new number by the original number
400 - 505 = -105
-105 ÷ 505 = -0.2079207920792079
-0.2079207920792079 x 100 = -20.79%