5. Вычисли: (1 1/4 · 2/5 + 3 3/7 : 9/14) : 5/12 − 10 1/5.

Преобразуем смешанные числа:

\(1\dfrac{1}{4}=\dfrac{5}{4}\), \(3\dfrac{3}{7}=\dfrac{24}{7}\), \(10\dfrac{1}{5}=\dfrac{51}{5}\).

\(\left(\dfrac{5}{4}\cdot\dfrac{2}{5}+\dfrac{24}{7}:\dfrac{9}{14}\right):\dfrac{5}{12}-\dfrac{51}{5}\)

\(=\left(\dfrac{1}{2}+\dfrac{24}{7}\cdot\dfrac{14}{9}\right):\dfrac{5}{12}-\dfrac{51}{5}\)

\(=\left(\dfrac{1}{2}+\dfrac{16}{3}\right):\dfrac{5}{12}-\dfrac{51}{5}=\dfrac{35}{6}\cdot\dfrac{12}{5}-\dfrac{51}{5}\)

\(=14-\dfrac{51}{5}=\dfrac{70}{5}-\dfrac{51}{5}=\dfrac{19}{5}=3\dfrac{4}{5}\).

Ответ: \(3\dfrac{4}{5}\).