\[\frac{3m - n}{4m - 6n};\ \ если\ \ \ m = - 2;\ \ \]
\[n = 1.\]
\[\frac{3m - n}{4m - 6n} = \frac{3m - n}{2 \cdot (2m - 3n)} =\]
\[= \frac{3 \cdot ( - 2) - 1}{2 \cdot \left( 2 \cdot ( - 2) - 3 \cdot 1 \right)} =\]