[tex]\bf \begin{array}{ccllll}
amount&\$\\
\textendash\textendash\textendash\textendash\textendash\textendash&\textendash\textendash\textendash\textendash\textendash\textendash\\
6&10\\
9&x
\end{array}\implies \cfrac{6}{9}=\cfrac{10}{x}[/tex]
solve for "x"
