2) (2,5 - 0,75) * 4/7 + [(3 3/8 - 2 11/12) * 1 7/9 + 2 11/12 * 1 7/9] : (3,5 : 2 2/3);

2) $$(2,5 - 0,75) \cdot \frac{4}{7} + [(3\frac{3}{8} - 2\frac{11}{12}) \cdot 1\frac{7}{9} + 2\frac{11}{12} \cdot 1\frac{7}{9}] : (3,5 : 2\frac{2}{3});$$

Выполним действия в скобках:

$$2,5 - 0,75 = 1,75 = \frac{175}{100} = \frac{7}{4}$$

$$3\frac{3}{8} = \frac{27}{8}$$

$$2\frac{11}{12} = \frac{35}{12}$$

$$\frac{27}{8} - \frac{35}{12} = \frac{81}{24} - \frac{70}{24} = \frac{11}{24}$$

$$1\frac{7}{9} = \frac{16}{9}$$

$$\frac{11}{24} \cdot \frac{16}{9} = \frac{11 \cdot 2}{3 \cdot 9} = \frac{22}{27}$$

$$\frac{35}{12} \cdot \frac{16}{9} = \frac{35 \cdot 4}{3 \cdot 9} = \frac{140}{27}$$

$$\frac{22}{27} + \frac{140}{27} = \frac{162}{27} = 6$$

$$3,5 : 2\frac{2}{3} = 3,5 : \frac{8}{3} = \frac{7}{2} \cdot \frac{3}{8} = \frac{21}{16}$$

$$6 : \frac{21}{16} = 6 \cdot \frac{16}{21} = 2 \cdot \frac{16}{7} = \frac{32}{7}$$

$$\frac{7}{4} \cdot \frac{4}{7} = 1$$

$$1 + \frac{32}{7} = \frac{7}{7} + \frac{32}{7} = \frac{39}{7} = 5\frac{4}{7}$$

Ответ: $$5\frac{4}{7}$$