so, we know the original price is 440, but it got dropped to 154, for a difference of 286.
so, if we take 440 to be the 100%, what is 286 off of it in percentage anyway?
[tex]\bf \begin{array}{ccll}
amount&\%\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
440&100\\
286&p
\end{array}\implies \cfrac{440}{286}=\cfrac{100}{p}\implies p=\cfrac{286\cdot 100}{440}[/tex]
