if we know that 115 is the 100%, what is 65 off of it in percentage?
[tex]\bf \begin{array}{ccll}
amount&\%\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
115&100\\
65&p
\end{array}\implies \cfrac{115}{65}=\cfrac{100}{p}\implies p=\cfrac{65\cdot 100}{115}[/tex]