13 Вычислите: 2$$\frac{11}{17}$$\cdot ($$\frac{3}{4}$$ - $$\frac{7}{15}$$) - 11:2$$\frac{3}{4}$$.

Выполним вычисления.

1. $$\frac{3}{4} - \frac{7}{15} = \frac{3 \cdot 15}{4 \cdot 15} - \frac{7 \cdot 4}{15 \cdot 4} = \frac{45}{60} - \frac{28}{60} = \frac{45-28}{60} = \frac{17}{60}$$
2. $$2\frac{11}{17} = \frac{2 \cdot 17 + 11}{17} = \frac{34 + 11}{17} = \frac{45}{17}$$
3. $$\frac{45}{17} \cdot \frac{17}{60} = \frac{45 \cdot 17}{17 \cdot 60} = \frac{45}{60} = \frac{3}{4}$$
4. $$2\frac{3}{4} = \frac{2 \cdot 4 + 3}{4} = \frac{8+3}{4} = \frac{11}{4}$$
5. $$11 : \frac{11}{4} = 11 \cdot \frac{4}{11} = \frac{11 \cdot 4}{11} = 4$$
6. $$\frac{3}{4} - 4 = \frac{3}{4} - \frac{4 \cdot 4}{4} = \frac{3}{4} - \frac{16}{4} = \frac{3-16}{4} = \frac{-13}{4} = -3\frac{1}{4}$$

Ответ: -3$$\frac{1}{4}$$