Найдите значение выражений: a) $$(\frac{2}{3} : \frac{4}{9})^2$$ б) $$(\frac{2}{3})^2 : (\frac{4}{9})^2$$ в) $$(\frac{2}{9} \cdot \frac{7}{8} : \frac{7}{18})^3$$

a) $$(\frac{2}{3} : \frac{4}{9})^2 = (\frac{2}{3} \cdot \frac{9}{4})^2 = (\frac{18}{12})^2 = (\frac{3}{2})^2 = \frac{9}{4} = 2\frac{1}{4}$$ б) $$(\frac{2}{3})^2 : (\frac{4}{9})^2 = \frac{4}{9} : \frac{16}{81} = \frac{4}{9} \cdot \frac{81}{16} = \frac{324}{144} = \frac{9}{4} = 2\frac{1}{4}$$ в) $$(\frac{2}{9} \cdot \frac{7}{8} : \frac{7}{18})^3 = (\frac{2 \cdot 7}{9 \cdot 8} : \frac{7}{18})^3 = (\frac{14}{72} : \frac{7}{18})^3 = (\frac{7}{36} : \frac{7}{18})^3 = (\frac{7}{36} \cdot \frac{18}{7})^3 = (\frac{18}{36})^3 = (\frac{1}{2})^3 = \frac{1}{8}$$ Ответ: а) $$2\frac{1}{4}$$, б) $$2\frac{1}{4}$$, в) $$\frac{1}{8}$$