17) -2 1/3 - 1/2

$$-2 \frac{1}{3} - \frac{1}{2} = -\frac{2 \cdot 3 + 1}{3} - \frac{1}{2} = -\frac{7}{3} - \frac{1}{2} = -\frac{7 \cdot 2 + 1 \cdot 3}{3 \cdot 2} = -\frac{14 + 3}{6} = -\frac{17}{6} = -2 \frac{5}{6}$$
Ответ: $$-2 \frac{5}{6}$$