-45% is the change from 400 to 220
Calculation steps:
[( 220 - 400 ) ÷ 400] x 100 = -45%
Formula
Percentage change = [(220 - 400) / 400] x 100
Subtract the new number by the original number
220 - 400 = -180
-180 ÷ 400 = -0.45
-0.45 x 100 = -45%
Example