11) \(\frac{4\cdot5}{6\cdot15}\) = \(\frac{2\cdot2\cdot5}{2\cdot3\cdot3\cdot5}\) = \(\frac{2}{3\cdot3}\) = \(\frac{2}{9}\)
Дробь \(\frac{2}{9}\) несократимая.
Ответ: \(\frac{2}{9}\)