23 : (6\frac{5}{17} + 1\frac{12}{17}) - (4\frac{2}{5} - 2\frac{3}{5}) : 5

Решение:

1. 6\frac{5}{17} = \frac{107}{17}
2. 1\frac{12}{17} = \frac{29}{17}
3. \frac{107}{17} + \frac{29}{17} = \frac{136}{17} = 8
4. 23 : 8 = 2.875
5. 4\frac{2}{5} = \frac{22}{5} = 4.4
6. 2\frac{3}{5} = \frac{13}{5} = 2.6
7. 4.4 - 2.6 = 1.8
8. 1.8 : 5 = 0.36
9. 2.875 - 0.36 = 2.515

Ответ: 2.515