3 \cdot 2\frac{7}{15} - 5\frac{1}{2} \cdot \frac{7}{9} + 1\frac{7}{48} \cdot 2\frac{2}{11} - \frac{2}{5} \cdot 6\frac{5}{9}

Решим пример по действиям:

1. $$3 \cdot 2\frac{7}{15} = 3 \cdot \frac{37}{15} = \frac{3 \cdot 37}{15} = \frac{37}{5} = 7\frac{2}{5}$$
2. $$5\frac{1}{2} \cdot \frac{7}{9} = \frac{11}{2} \cdot \frac{7}{9} = \frac{11 \cdot 7}{2 \cdot 9} = \frac{77}{18} = 4\frac{5}{18}$$
3. $$1\frac{7}{48} \cdot 2\frac{2}{11} = \frac{55}{48} \cdot \frac{24}{11} = \frac{55 \cdot 24}{48 \cdot 11} = \frac{5 \cdot 1}{2 \cdot 1} = \frac{5}{2} = 2\frac{1}{2}$$
4. $$\frac{2}{5} \cdot 6\frac{5}{9} = \frac{2}{5} \cdot \frac{59}{9} = \frac{2 \cdot 59}{5 \cdot 9} = \frac{118}{45} = 2\frac{28}{45}$$
5. $$7\frac{2}{5} - 4\frac{5}{18} = 7\frac{36}{90} - 4\frac{25}{90} = 3\frac{11}{90}$$
6. $$2\frac{1}{2} - 2\frac{28}{45} = 2\frac{45}{90} - 2\frac{56}{90} = \frac{45}{90} - \frac{56}{90} = -\frac{11}{90}$$
7. $$3\frac{11}{90} - \frac{11}{90} = 3$$

Ответ: 3