26. 4 1/7 - 2 3/5

$$4 \frac{1}{7} - 2 \frac{3}{5} = (4-2) + (\frac{1}{7} - \frac{3}{5}) = 2 + (\frac{1 \cdot 5}{7 \cdot 5} - \frac{3 \cdot 7}{5 \cdot 7}) = 2 + (\frac{5}{35} - \frac{21}{35}) = 2 - \frac{16}{35} = 1 \frac{35}{35} - \frac{16}{35} = 1 \frac{19}{35}$$

Ответ: $$1 \frac{19}{35}$$