1. Вычислите: 1. $$\frac{7}{9} - \frac{5}{6} \cdot \frac{4}{15}$$ 2. $$\left(\frac{2}{3} - \frac{2}{9}\right) : \frac{4}{8}$$ 3. $$\frac{2}{7} + \frac{3}{8} : \frac{7}{32}$$ 4. $$7,56 + (346 - 83,6) : 12,8$$

1. Вычислите:

1. 1.
   $$\frac{7}{9} - \frac{5}{6} \cdot \frac{4}{15} = \frac{7}{9} - \frac{5 \cdot 4}{6 \cdot 15} = \frac{7}{9} - \frac{20}{90} = \frac{7}{9} - \frac{2}{9} = \frac{5}{9}$$
2. 2.
   $$\left(\frac{2}{3} - \frac{2}{9}\right) : \frac{4}{8} = \left(\frac{6}{9} - \frac{2}{9}\right) : \frac{1}{2} = \frac{4}{9} : \frac{1}{2} = \frac{4}{9} \cdot 2 = \frac{8}{9}$$
3. 3.
   $$\frac{2}{7} + \frac{3}{8} : \frac{7}{32} = \frac{2}{7} + \frac{3}{8} \cdot \frac{32}{7} = \frac{2}{7} + \frac{3 \cdot 4}{7} = \frac{2}{7} + \frac{12}{7} = \frac{14}{7} = 2$$
4. 4.
   $$7,56 + (346 - 83,6) : 12,8 = 7,56 + 262,4 : 12,8 = 7,56 + 20,5 = 28,06$$

Ответ: 1. $$\frac{5}{9}$$; 2. $$\frac{8}{9}$$; 3. $$2$$; 4. $$28,06$$.