№1. Найдите произведение или частное:

a) \(\frac{9}{10} \cdot \frac{5}{12} = \frac{9 \cdot 5}{10 \cdot 12} = \frac{45}{120} = \frac{3 \cdot 15}{8 \cdot 15} = \frac{3}{8}\) б) \(\frac{3}{5} \cdot \frac{11}{15} = \frac{3 \cdot 11}{5 \cdot 15} = \frac{33}{75} = \frac{11 \cdot 3}{25 \cdot 3} = \frac{11}{25}\) в) \(\frac{9}{22} \cdot \frac{2}{3} = \frac{9 \cdot 2}{22 \cdot 3} = \frac{18}{66} = \frac{3 \cdot 6}{11 \cdot 6} = \frac{3}{11}\) г) \(\frac{7}{8} : \frac{7}{16} = \frac{7}{8} \cdot \frac{16}{7} = \frac{7 \cdot 16}{8 \cdot 7} = \frac{16}{8} = 2\) д) \(\frac{40}{27} : \frac{18}{35} = \frac{40}{27} \cdot \frac{35}{18} = \frac{40 \cdot 35}{27 \cdot 18} = \frac{1400}{486} = \frac{700}{243} = 2 \frac{214}{243}\) е) \(\frac{8}{9} : \frac{6}{5} = \frac{8}{9} \cdot \frac{5}{6} = \frac{8 \cdot 5}{9 \cdot 6} = \frac{40}{54} = \frac{20 \cdot 2}{27 \cdot 2} = \frac{20}{27}\) ж) \(15 \cdot \frac{5}{6} = \frac{15}{1} \cdot \frac{5}{6} = \frac{15 \cdot 5}{1 \cdot 6} = \frac{75}{6} = \frac{25 \cdot 3}{2 \cdot 3} = \frac{25}{2} = 12 \frac{1}{2}\) з) \(1 : \frac{3}{7} = \frac{1}{1} \cdot \frac{7}{3} = \frac{7}{3} = 2 \frac{1}{3}\) и) \(\frac{2}{3} \cdot 12 = \frac{2}{3} \cdot \frac{12}{1} = \frac{2 \cdot 12}{3 \cdot 1} = \frac{24}{3} = 8\) к) \(\frac{2}{3} : 18 = \frac{2}{3} \cdot \frac{1}{18} = \frac{2}{54} = \frac{1}{27}\) л) \(\frac{8}{27} : 36 = \frac{8}{27} \cdot \frac{1}{36} = \frac{8}{972} = \frac{2}{243}\) м) \(10 : \frac{4}{15} = \frac{10}{1} \cdot \frac{15}{4} = \frac{150}{4} = \frac{75}{2} = 37 \frac{1}{2}\)