Ответ:

а) \(\frac{9}{15}=\frac{9:3}{15:3}=\frac{3}{5}\).

б) \(\frac{36}{120}=\frac{36:12}{120:12}=\frac{3}{10}\).

в) \(\frac{45}{105}=\frac{45:15}{105:15}=\frac{3}{7}\).

г) \(\frac{180}{900}=\frac{180:180}{900:180}=\frac{1}{5}\).

Ответ: а) \(\frac{3}{5}\); б) \(\frac{3}{10}\); в) \(\frac{3}{7}\); г) \(\frac{1}{5}\).