12 Выполните деление.

Решение:

1. \( \frac{3}{4} : \frac{9}{16} = \frac{3}{4} \times \frac{16}{9} = \frac{3 \times 16}{4 \times 9} = \frac{48}{36} \)
2. \( \frac{8}{15} : \frac{4}{15} = \frac{8}{15} \times \frac{15}{4} = \frac{8 \times 15}{15 \times 4} = \frac{120}{60} \)
3. \( \frac{31}{41} : \frac{8}{41} = \frac{31}{41} \times \frac{41}{8} = \frac{31 \times 41}{41 \times 8} = \frac{1271}{328} \)
4. \( 9 : \frac{27}{5} = 9 \times \frac{5}{27} = \frac{9 \times 5}{27} = \frac{45}{27} \)

Ответ: 1) \( \frac{48}{36} \), 2) \( \frac{120}{60} \), 3) \( \frac{1271}{328} \), 4) \( \frac{45}{27} \).