Ответ:

  1. \(\frac{2}{13}\cdot5=\frac{10}{13}\).
  2. \(\frac{4}{17}\cdot3=\frac{12}{17}\).
  3. \(\frac{8}{9}\cdot2=\frac{16}{9}=1\frac{7}{9}\).
  4. \(\frac{4}{49}\cdot7=\frac{4}{7}\).
  5. \(7\cdot\frac{3}{40}=\frac{21}{40}\).
  6. \(6\cdot\frac{15}{18}=\frac{90}{18}=5\).
  7. \(\frac{7}{12}\cdot24=7\cdot2=14\).
  8. \(45\cdot\frac{8}{15}=3\cdot8=24\).