-5.5% is the change from 400 to 378
Calculation steps:
[( 378 - 400 ) ÷ 400] x 100 = -5.5%
Formula
Percentage change = [(378 - 400) / 400] x 100
Subtract the new number by the original number
378 - 400 = -22
-22 ÷ 400 = -0.055
-0.055 x 100 = -5.5%
Example