12. Вычислите: \(9\frac{2}{3} \times 6\frac{4}{7}\).

\(9\frac{2}{3}=\frac{29}{3}\), \(6\frac{4}{7}=\frac{46}{7}\).

\(\frac{29}{3}\times\frac{46}{7}=\frac{1334}{21}=63\frac{11}{21}\).

Ответ: \(63\frac{11}{21}\).