4 Упростите и найдите значение выражения: 4/5 m + 9 6/7 n - 3/5 m - 5 2/7 n при m = 11 1/14 , n = 2 5/8.

$$ \frac{4}{5} m + 9 \frac{6}{7} n - \frac{3}{5} m - 5 \frac{2}{7} n = (\frac{4}{5} - \frac{3}{5}) m + (9 \frac{6}{7} - 5 \frac{2}{7}) n = \frac{1}{5} m + 4 \frac{4}{7} n = \frac{1}{5} m + \frac{32}{7} n $$

При m = $$11 \frac{1}{14} = \frac{155}{14}$$, n = $$2 \frac{5}{8} = \frac{21}{8}$$

$$\frac{1}{5} m + \frac{32}{7} n = \frac{1}{5} \cdot \frac{155}{14} + \frac{32}{7} \cdot \frac{21}{8} = \frac{155}{70} + \frac{32 \cdot 21}{7 \cdot 8} = \frac{155}{70} + \frac{4 \cdot 3}{1} = \frac{155}{70} + 12 = \frac{155 + 12 \cdot 70}{70} = \frac{155 + 840}{70} = \frac{995}{70} = \frac{199}{14} = 14 \frac{3}{14}$$

Ответ: $$14 \frac{3}{14}$$