\[\boxed{\mathbf{860\ (860).\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
\[1)\ \frac{2xy - y^{2}}{9} \cdot \frac{36}{y^{4}} =\]
\[= \frac{y(2x - y) \cdot 36}{9y^{4}} = \frac{4 \cdot (2x - y)}{y^{3}}\]
\[2)\ \frac{a^{2} - 7ab}{a^{2} + 2ab} \cdot \frac{a^{2}b + 2ab^{2}}{a^{3} - 7a^{2}b} =\]
\[= \frac{a(a - 7b) \cdot ab(a + 2b)}{a(a + 2b) \cdot a²(a - 7b)} = \frac{b}{a}\]
\[3)\ \frac{m^{2} - 64}{m^{3} - 9m^{2}} \cdot \frac{m^{2} - 81}{m^{2} + 8m} =\]
\[= \frac{(m - 8)(m + 9)}{m³}\]
\[4)\ \frac{2x^{2} - 16x + 32}{3x^{2} - 6x + 12} \cdot \frac{x^{3} + 8}{4x^{2} - 64} =\]
\[= \frac{(x - 4)(x + 2)}{6 \cdot (x + 4)}\]