1. $$2\frac{3}{4}+3\frac{5}{7}$$ 2. $$-4\frac{2}{3}+7\frac{1}{2}$$ 3. $$4\frac{1}{3}+\frac{3}{17}$$ 4. $$-5\frac{2}{5}+4\frac{1}{3}$$ 5. $$6\frac{1}{2}-3\frac{3}{4}$$ 6. $$2\frac{1}{2}-\frac{5}{6}$$ 7. $$-4\frac{2}{3}-7\frac{7}{9}$$ 8. $$-2\frac{2}{3}-3\frac{5}{9}$$

Решение:

1. $$2\frac{3}{4}+3\frac{5}{7} = 2+3+\frac{3}{4}+\frac{5}{7} = 5+\frac{21+20}{28} = 5\frac{41}{28} = 6\frac{13}{28}$$
2. $$-4\frac{2}{3}+7\frac{1}{2} = -\frac{14}{3}+\frac{15}{2} = \frac{-28+45}{6} = \frac{17}{6} = 2\frac{5}{6}$$
3. $$4\frac{1}{3}+\frac{3}{17} = \frac{13}{3}+\frac{3}{17} = \frac{13\cdot 17+3\cdot 3}{51} = \frac{221+9}{51} = \frac{230}{51}$$
4. $$-5\frac{2}{5}+4\frac{1}{3} = -\frac{27}{5}+\frac{13}{3} = \frac{-81+65}{15} = -\frac{16}{15} = -1\frac{1}{15}$$
5. $$6\frac{1}{2}-3\frac{3}{4} = \frac{13}{2}-\frac{15}{4} = \frac{26-15}{4} = \frac{11}{4} = 2\frac{3}{4}$$
6. $$2\frac{1}{2}-\frac{5}{6} = \frac{5}{2}-\frac{5}{6} = \frac{15-5}{6} = \frac{10}{6} = \frac{5}{3} = 1\frac{2}{3}$$
7. $$-4\frac{2}{3}-7\frac{7}{9} = -\frac{14}{3}-\frac{70}{9} = \frac{-42-70}{9} = -\frac{112}{9} = -12\frac{4}{9}$$
8. $$-2\frac{2}{3}-3\frac{5}{9} = -\frac{8}{3}-\frac{32}{9} = \frac{-24-32}{9} = -\frac{56}{9} = -6\frac{2}{9}$$

Ответ: 1. $$6\frac{13}{28}$$; 2. $$2\frac{5}{6}$$; 3. $$\frac{230}{51}$$; 4. $$-1\frac{1}{15}$$; 5. $$2\frac{3}{4}$$; 6. $$1\frac{2}{3}$$; 7. $$-12\frac{4}{9}$$; 8. $$-6\frac{2}{9}$$.