400% is the change from 18 to 90
Calculation steps:
[( 90 - 18 ) ÷ 18] x 100 = 400%
Formula
Percentage change = [(90 - 18) / 18] x 100
Subtract the new number by the original number
90 - 18 = 72
72 ÷ 18 = 4
4 x 100 = 400%
Example