1. \(\frac{8}{12} = \frac{2}{3}\) (на \(4\)); 2. \(\frac{12}{16} = \frac{3}{4}\) (на \(4\)); 3. \(\frac{24}{18} = \frac{4}{3}\) (на \(6\)); 4. \(\frac{8}{40} = \frac{1}{5}\) (на \(8\)); 5. \(\frac{18}{27} = \frac{2}{3}\) (на \(9\)); 6. \(\frac{8}{36} = \frac{2}{9}\) (на \(4\)); 7. \(\frac{20}{30} = \frac{2}{3}\) (на \(10\)); 8. \(\frac{30}{90} = \frac{1}{3}\) (на \(30\)); 9. \(\frac{7}{21} = \frac{1}{3}\) (на \(7\)); 10. \(\frac{8}{24} = \frac{1}{3}\) (на \(8\)).