-17.5% is the change from 400 to 330
Calculation steps:
[( 330 - 400 ) ÷ 400] x 100 = -17.5%
Formula
Percentage change = [(330 - 400) / 400] x 100
Subtract the new number by the original number
330 - 400 = -70
-70 ÷ 400 = -0.175
-0.175 x 100 = -17.5%