-20.16% is the change from 501 to 400
Calculation steps:
[( 400 - 501 ) ÷ 501] x 100 = -20.16%
Formula
Percentage change = [(400 - 501) / 501] x 100
Subtract the new number by the original number
400 - 501 = -101
-101 ÷ 501 = -0.20159680638722555
-0.20159680638722555 x 100 = -20.16%