3

Решение:

Выполним действия по порядку:

1. \( 2 \frac{5}{6} = \frac{17}{6} \)
2. \( \frac{17}{6} \cdot \frac{3}{7} = \frac{17}{2} \cdot \frac{1}{7} = \frac{17}{14} \)
3. \( \frac{8}{25} : 0,4 = \frac{8}{25} : \frac{2}{5} = \frac{8}{25} \cdot \frac{5}{2} = \frac{4}{5} \cdot \frac{1}{1} = \frac{4}{5} \)
4. \( \frac{17}{14} - \frac{4}{5} = \frac{17 \cdot 5 - 4 \cdot 14}{70} = \frac{85 - 56}{70} = \frac{29}{70} \)
5. \( 2 \frac{1}{17} = \frac{35}{17} \)
6. \( 3 \frac{4}{7} = \frac{25}{7} \)
7. \( \frac{29}{70} \cdot \frac{35}{17} = \frac{29}{2} \cdot \frac{1}{17} = \frac{29}{34} \)
8. \( \frac{25}{7} \cdot 0,28 = \frac{25}{7} \cdot \frac{28}{100} = \frac{25}{1} \cdot \frac{4}{100} = \frac{100}{100} = 1 \)
9. \( \frac{29}{34} + 1 = \frac{29}{34} + \frac{34}{34} = \frac{63}{34} \)

Ответ: \(\frac{63}{34}\)