Выполните деление:

a) $$\frac{3n}{4m} : \frac{27n^4}{16} = \frac{3n}{4m} \cdot \frac{16}{27n^4} = \frac{3 \cdot 16 \cdot n}{4 \cdot 27 \cdot m \cdot n^4} = \frac{4 \cdot 1}{1 \cdot 9 \cdot m \cdot n^3} = \frac{4}{9mn^3}$$.

в) $$26x^7 : \frac{39x^4}{5y} = 26x^7 \cdot \frac{5y}{39x^4} = \frac{26 \cdot 5 \cdot x^7 \cdot y}{39 \cdot x^4} = \frac{2 \cdot 5 \cdot x^3 \cdot y}{3} = \frac{10x^3y}{3}$$.

б) $$\frac{36a^5}{11b} : (12a^3b^2) = \frac{36a^5}{11b} \cdot \frac{1}{12a^3b^2} = \frac{36a^5}{11b \cdot 12a^3b^2} = \frac{36a^5}{132a^3b^3} = \frac{3a^2}{11b^3}$$.

г) $$\frac{15xy}{7ab} : (\frac{10x^4y}{21a^3b^2}) = \frac{15xy}{7ab} \cdot \frac{21a^3b^2}{10x^4y} = \frac{15xy \cdot 21a^3b^2}{7ab \cdot 10x^4y} = \frac{315a^3b^2xy}{70abx^4y} = \frac{9a^2b}{2x^3}$$.