-18% is the change from 400 to 328
Calculation steps:
[( 328 - 400 ) ÷ 400] x 100 = -18%
Formula
Percentage change = [(328 - 400) / 400] x 100
Subtract the new number by the original number
328 - 400 = -72
-72 ÷ 400 = -0.18
-0.18 x 100 = -18%
Example