so the original price was 450, and it got marked down to 382.50, so it got discounted by 67.5 bucks.
if we take 450 to be the 100%, what is 67.5 off of it in percentage?
[tex]\bf \begin{array}{ccll}
amount&\%\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
450&100\\
67.5&p
\end{array}\implies \cfrac{450}{67.5}=\cfrac{100}{p}\implies p=\cfrac{67.5\cdot 100}{450}[/tex]