well, the original price was 500 bucks, but went down to 325, namely 500 - 325 = 175, so she'll be saving 175 bucks.
if we take 500 to be the 100%, what is 175 off of it in percentage?
[tex]\begin{array}{ccll} amount&\%\\ \cline{1-2} 500 & 100\\ 175& x \end{array} \implies \cfrac{500}{175}=\cfrac{100}{x}\implies \cfrac{20}{7}=\cfrac{100}{x} \\\\\\ 20x=700\implies x=\cfrac{700}{20}\implies x=35[/tex]
