47. \(\frac{11}{12} : \frac{7}{12} \times \frac{21}{55}\)

Решение:

\(\frac{11}{12} \div \frac{7}{12} \times \frac{21}{55} = \frac{11}{12} \times \frac{12}{7} \times \frac{21}{55} = \frac{11 \times 12 \times 21}{12 \times 7 \times 55} = \frac{11 \times 21}{7 \times 55} = \frac{11 \times 3 \times 7}{7 \times 5 \times 11} = \frac{3}{5}\)

Ответ: \(\frac{3}{5}\)