6. Найдите значение выражения: a) $$2\frac{1}{7} : 4\frac{1}{3} \cdot 2\frac{1}{3}$$ б) $$30\frac{5}{6} + (7\frac{1}{3} + 2\frac{1}{4}) : \frac{1}{4}$$

a) $$2\frac{1}{7} : 4\frac{1}{3} \cdot 2\frac{1}{3} = \frac{15}{7} : \frac{13}{3} \cdot \frac{7}{3} = \frac{15}{7} \cdot \frac{3}{13} \cdot \frac{7}{3} = \frac{15 \cdot 3 \cdot 7}{7 \cdot 13 \cdot 3} = \frac{15}{13} = 1\frac{2}{13}$$ **Ответ: $$1\frac{2}{13}$$** б) $$30\frac{5}{6} + (7\frac{1}{3} + 2\frac{1}{4}) : \frac{1}{4} = 30\frac{5}{6} + (\frac{22}{3} + \frac{9}{4}) : \frac{1}{4} = 30\frac{5}{6} + (\frac{22 \cdot 4}{3 \cdot 4} + \frac{9 \cdot 3}{4 \cdot 3}) : \frac{1}{4} = 30\frac{5}{6} + (\frac{88}{12} + \frac{27}{12}) : \frac{1}{4} = 30\frac{5}{6} + \frac{115}{12} : \frac{1}{4} = 30\frac{5}{6} + \frac{115}{12} \cdot 4 = 30\frac{5}{6} + \frac{115}{3} = 30\frac{5}{6} + 38\frac{1}{3} = 30\frac{5}{6} + 38\frac{2}{6} = 68\frac{7}{6} = 69\frac{1}{6}$$ **Ответ: $$69\frac{1}{6}$$**