а) \(\frac{5}{6} \cdot \frac{7}{9} = \frac{5 \cdot 7}{6 \cdot 9} = \frac{35}{54}\)
б) \(\frac{11}{28} \cdot \frac{7}{33} = \frac{11 \cdot 7}{28 \cdot 33} = \frac{1 \cdot 1}{4 \cdot 3} = \frac{1}{12}\)
в) \(1 \frac{8}{25} \cdot \frac{4}{11} = \frac{33}{25} \cdot \frac{4}{11} = \frac{3 \cdot 11 \cdot 4}{25 \cdot 11} = \frac{12}{25}\)
г) \(3 \frac{5}{7} \cdot \frac{1}{13} = \frac{26}{7} \cdot \frac{1}{13} = \frac{2 \cdot 13 \cdot 1}{7 \cdot 13} = \frac{2}{7}\)
Ответ: а) \(\frac{35}{54}\); б) \(\frac{1}{12}\); в) \(\frac{12}{25}\); г) \(\frac{2}{7}\).