\[\boxed{\mathbf{1.}\mathbf{78}\mathbf{.\ ОК\ ГДЗ - домашка\ на\ }5}\]
\[\textbf{а)}\ \frac{4}{9} \cdot \frac{63}{64} \cdot \frac{2}{7} = \frac{8 \cdot 63}{63 \cdot 64} = \frac{1}{8}\]
\[\textbf{б)}\ \left( \frac{1}{2} \right)^{2}\ :\frac{5}{6}\ :\frac{7}{15} = \frac{1}{4} \cdot \frac{6}{5} \cdot \frac{15}{7} =\]
\[= \frac{3 \cdot 3}{2 \cdot 7} = \frac{9}{14}\]
\[\textbf{в)}\ \left( 1^{\backslash 3} - \frac{1}{3} \right)\ :\left( \frac{1^{\backslash 4}}{3} - \frac{1^{\backslash 3}}{4} \right) =\]
\[= \frac{2}{3}\ :\frac{1}{12} = \frac{2}{3} \cdot 12 = 2 \cdot 4 = 8\]