3. Сравните: 1) \(\frac{18}{24}\) и \(\frac{9}{12}\); 2) \(\frac{20}{25}\) и \(\frac{12}{15}\).

1. Сократим дроби: \(\frac{18}{24}=\frac{3}{4}\), \(\frac{9}{12}=\frac{3}{4}\). Следовательно, \(\frac{18}{24}=\frac{9}{12}\).
2. Сократим дроби: \(\frac{20}{25}=\frac{4}{5}\), \(\frac{12}{15}=\frac{4}{5}\). Следовательно, \(\frac{20}{25}=\frac{12}{15}\).

Ответ: 1) \(\frac{18}{24}=\frac{9}{12}\); 2) \(\frac{20}{25}=\frac{12}{15}\).