SOLUTION:
Since,
\[\begin{array}{*{35}{l}}
3\left( m\text{ }+\text{ }n \right)\text{ }=\text{ }2\left( m\text{ }+\text{ }3n \right) \\
3m\text{ }+\text{ }3n\text{ }=\text{ }2m\text{ }+\text{ }6n \\
m\text{ }=\text{ }3n \\
m/n\text{ }=\text{ }3/1 \\
\end{array}\]