If y varies directly as x, we can write the following equation:
[tex]\frac{y}{x}=k[/tex]When x = 3, we have y = 6, so:
[tex]\begin{gathered} \frac{6}{3}=k \\ k=2 \end{gathered}[/tex]Now, using x = 9, we have:
[tex]\begin{gathered} \frac{y}{9}=2 \\ y=18 \end{gathered}[/tex]Therefore the answer is y = 18.
