\[\boxed{\text{156\ (156).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
Пояснение.
Решение.
\[1)\frac{3a^{4}b^{3}}{10c^{5}} \cdot \frac{4b^{4}c^{2}}{27a^{7}}\ :\frac{5b^{7}}{9a^{3}c^{3}} =\]
\[= \frac{3a^{4}b^{3} \cdot 4b^{4}c^{2} \cdot 9a^{3}c^{3}}{10c^{5} \cdot 27a^{7} \cdot 5b^{7}} = \frac{2}{25}\]
\[2)\frac{3a^{2}}{2b^{2}c^{2}}\ :\frac{7c^{8}}{6b^{3}}\ :\frac{9ab}{14c^{12}} =\]
\[= \frac{3a^{2} \cdot 6b^{3} \cdot 14c^{12}}{2b^{2}c^{2} \cdot 7c^{8} \cdot 9ab} = \frac{2ac^{2}}{1} =\]
\[= 2ac^{2}\]
\[3)\ \left( \frac{5a^{3}}{b^{4}} \right)^{4} \cdot \frac{b^{18}}{50a^{16}} =\]
\[= \frac{25 \cdot 25 \cdot a^{12} \cdot b^{18}}{b^{16} \cdot 50a^{16}} = \frac{25b^{2}}{2a^{4}}\]
\[4)\ \left( \frac{3x^{7}}{y^{10}} \right)^{4}:\left( \frac{3x^{6}}{y^{8}} \right)^{3} =\]
\[= \frac{3^{4} \cdot x^{28} \cdot y^{24}}{y^{40} \cdot 3^{3} \cdot x^{18}} = \frac{3x^{10}}{y^{16}}\]