№3 a) \(\frac{3}{8} \div \frac{9}{16}\); б) \( 48 \div \frac{12}{13}\); в) \(\frac{11}{28} \div \frac{7}{33}\); г) \( 2\frac{2}{3} \cdot 6\); д) \( 7\frac{11}{12} \div 3\frac{1}{6}\).

Решение:

1. \(\frac{3}{8} \div \frac{9}{16} = \frac{3}{8} \times \frac{16}{9} = \frac{3 \times 16}{8 \times 9} = \frac{1 \times 2}{1 \times 3} = \frac{2}{3}\)
2. \( 48 \div \frac{12}{13} = 48 \times \frac{13}{12} = \frac{48 \times 13}{12} = 4 \times 13 = 52 \)
3. \(\frac{11}{28} \div \frac{7}{33} = \frac{11}{28} \times \frac{33}{7} = \frac{11 \times 33}{28 \times 7} = \frac{363}{196}\)
4. \( 2\frac{2}{3} \times 6 = \frac{8}{3} \times 6 = \frac{8 \times 6}{3} = 8 \times 2 = 16 \)
5. \( 7\frac{11}{12} \div 3\frac{1}{6} = \frac{95}{12} \div \frac{19}{6} = \frac{95}{12} \times \frac{6}{19} = \frac{95 \times 6}{12 \times 19} = \frac{5 \times 1}{2 \times 1} = \frac{5}{2} = 2\frac{1}{2} \)

Ответ: а) \(\frac{2}{3}\); б) 52; в) \(\frac{363}{196}\); г) 16; д) \(2\frac{1}{2}\).