\[\frac{x - 3y}{y} = 12 \Longrightarrow \frac{x}{y} - \frac{3y}{y} =\]
\[= 12 \Longrightarrow \frac{x}{y} - 3 = 12 \Longrightarrow \frac{x}{y} =\]
\[= 15 \Longrightarrow x = 15y\]
\[\frac{x}{y} = 15\]