18m2/5n-3 * 15n2/6m

3.

$$ \frac{18m^2}{5n^{-3}} \cdot \frac{15n^2}{6m} = \frac{18 \cdot 15}{5 \cdot 6} \cdot \frac{m^2}{m} \cdot \frac{n^2}{n^{-3}} = \frac{3 \cdot 3}{1 \cdot 1} \cdot m^{2-1} \cdot n^{2-(-3)} = 9mn^5$$.

Ответ: $$9mn^5$$