-12.5% is the change from 400 to 350
Calculation steps:
[( 350 - 400 ) ÷ 400] x 100 = -12.5%
Formula
Percentage change = [(350 - 400) / 400] x 100
Subtract the new number by the original number
350 - 400 = -50
-50 ÷ 400 = -0.125
-0.125 x 100 = -12.5%