12. $$\left(6 - 2\frac{4}{5}\right) \cdot 3\frac{1}{8} - 1\frac{1}{5} : \frac{3}{4}$$

INSIGHT

Решение:

1. \(6 - 2\frac{4}{5} = 6 - \frac{14}{5} = \frac{30 - 14}{5} = \frac{16}{5}\)
2. \(3\frac{1}{8} = \frac{25}{8}\)
3. \(\frac{16}{5} \cdot \frac{25}{8} = \frac{16 \cdot 25}{5 \cdot 8} = \frac{2 \cdot 5}{1 \cdot 1} = 10\)
4. \(1\frac{1}{5} = \frac{6}{5}\)
5. \(\frac{6}{5} : \frac{3}{4} = \frac{6}{5} \cdot \frac{4}{3} = \frac{6 \cdot 4}{5 \cdot 3} = \frac{2 \cdot 4}{5 \cdot 1} = \frac{8}{5}\)
6. \(10 - \frac{8}{5} = \frac{50 - 8}{5} = \frac{42}{5}\)

Ответ: \(\frac{42}{5}\)