г) $$ \frac{-39x^{18}y^{29}}{-13x^{19}y^{39}} = \frac{-39}{-13} \cdot \frac{x^{18}}{x^{19}} \cdot \frac{y^{29}}{y^{39}} = 3 \cdot x^{18-19} \cdot y^{29-39} = 3 \cdot x^{-1} \cdot y^{-10} = \frac{3}{xy^{10}} $$
Ответ: $$ \frac{3}{xy^{10}} $$