Ответ:

  1. Сократим множители: \(\frac{5}{18}\cdot15=\frac{5}{18}\cdot\frac{15}{1}=\frac{25}{6}\).

  2. \(\frac{49}{18}\cdot\frac{36}{21}=\frac{49}{21}\cdot2=\frac{7}{3}\cdot2=\frac{14}{3}\).

  3. \(\frac{52}{18}\cdot\frac{36}{13}=4\cdot2=8\).

  4. \(\frac{5}{144}\cdot\frac{24}{20}=\frac{5}{20}\cdot\frac{24}{144}=\frac{1}{4}\cdot\frac{1}{6}=\frac{1}{24}\).

  5. \(\frac{7}{12}\cdot\frac{75}{105}=\frac{7}{12}\cdot\frac{5}{7}=\frac{5}{12}\).

Ответ: 25/6; 14/3; 8; 1/24; 5/12.