12) (6 − 2 4/5) · 3 1/8 − 1 3/5 : 1/4

\((6-2\frac{4}{5})\cdot3\frac{1}{8}=\frac{16}{5}\cdot\frac{25}{8}=10\).

\(1\frac{3}{5}:\frac{1}{4}=\frac{8}{5}\cdot4=\frac{32}{5}\).

\(10-\frac{32}{5}=\frac{18}{5}\).

Ответ: \(\frac{18}{5}\).