№2 а) \(\frac{2}{3}\) : \(\frac{6}{7}\) : \(\frac{4}{7}\);

а) \(\frac{2}{3}\) : \(\frac{6}{7}\) : \(\frac{4}{7}\) = \(\frac{2}{3}\) * \(\frac{7}{6}\) * \(\frac{7}{4}\) = \(\frac{2*7*7}{3*6*4}\) = \(\frac{98}{72}\) = \(\frac{49}{36}\) = 1\(\frac{13}{36}\)

Ответ: 1\(\frac{13}{36}\)