**Решение:**
a) $$\frac{11}{17} + (-\frac{7}{17}) = \frac{11 - 7}{17} = \frac{4}{17}$$
б) $$\frac{9}{22} - \frac{13}{22} = \frac{9 - 13}{22} = \frac{-4}{22} = -\frac{2}{11}$$
в) $$\frac{4}{7} + (-\frac{6}{7}) = \frac{4 - 6}{7} = \frac{-2}{7} = -\frac{2}{7}$$
г) $$-\frac{12}{19} - \frac{7}{19} = \frac{-12 - 7}{19} = \frac{-19}{19} = -1$$
**Ответы:**
a) $$\frac{4}{17}$$
б) $$-\frac{2}{11}$$
в) $$-\frac{2}{7}$$
г) -1