Выполните действие: a) $$\frac{5}{14}:\frac{25}{6} \cdot \frac{7}{8}$$, б) $$\frac{4}{5}:(-\frac{2}{3})^{2} \cdot (-\frac{6}{5})^{2}$$, в) $$\(-\frac{2}{3})^{2} - 26$$, г) $$\frac{1}{2} : 2 \frac{1}{6}$$

a) $$\frac{5}{14} : \frac{25}{6} \cdot \frac{7}{8} = \frac{5}{14} \cdot \frac{6}{25} \cdot \frac{7}{8} = \frac{5 \cdot 6 \cdot 7}{14 \cdot 25 \cdot 8} = \frac{5 \cdot 2 \cdot 3 \cdot 7}{2 \cdot 7 \cdot 5 \cdot 5 \cdot 2 \cdot 4} = \frac{3}{5 \cdot 2 \cdot 4} = \frac{3}{40}$$

б) $$\frac{4}{5} : (-\frac{2}{3})^{2} \cdot (-\frac{6}{5})^{2} = \frac{4}{5} : \frac{4}{9} \cdot \frac{36}{25} = \frac{4}{5} \cdot \frac{9}{4} \cdot \frac{36}{25} = \frac{4 \cdot 9 \cdot 36}{5 \cdot 4 \cdot 25} = \frac{9 \cdot 36}{5 \cdot 25} = \frac{324}{125} = 2 \frac{74}{125}$$

в) $$(-\frac{2}{3})^{2} - 26 = \frac{4}{9} - 26 = \frac{4}{9} - \frac{26 \cdot 9}{9} = \frac{4 - 234}{9} = \frac{-230}{9} = -25 \frac{5}{9}$$

г) $$\frac{1}{2} : 2 \frac{1}{6} = \frac{1}{2} : \frac{13}{6} = \frac{1}{2} \cdot \frac{6}{13} = \frac{6}{26} = \frac{3}{13}$$