well if 18 out of 25 like it, then the remaining 7 doesn't like it, namely 7 out of 25.
if we take 25 to be the 100%, what is 7 off of if in percentage?
[tex]\bf \begin{array}{ccll} amount&\%\\ \cline{1-2} 25&100\\ 7&x \end{array}\implies \cfrac{25}{7}=\cfrac{100}{x}\implies 25x=700\implies x=\cfrac{700}{25}\implies x=28[/tex]
