2 4 8-3 = 7

8 2/7 - 3 4/7 = 4 5/7

$$8 \frac{2}{7} - 3 \frac{4}{7} = (8 - 3) + (\frac{2}{7} - \frac{4}{7}) = 5 - \frac{2}{7} = 4 \frac{7}{7} - \frac{2}{7} = 4 \frac{5}{7}$$

Или

$$8 \frac{2}{7} - 3 \frac{4}{7} = \frac{8 \cdot 7 + 2}{7} - \frac{3 \cdot 7 + 4}{7} = \frac{56+2}{7} - \frac{21+4}{7} = \frac{58}{7} - \frac{25}{7} = \frac{58-25}{7} = \frac{33}{7} = 4 \frac{5}{7}$$

Ответ: $$4 \frac{5}{7}$$