Вычислите:

1. $$6\frac{4}{9}+3\frac{5}{9} = (6+3) + (\frac{4}{9} + \frac{5}{9}) = 9 + \frac{9}{9} = 9 + 1 = 10$$
2. $$10\frac{11}{19}+5\frac{14}{19} = (10+5) + (\frac{11}{19} + \frac{14}{19}) = 15 + \frac{25}{19} = 15 + 1\frac{6}{19} = 16\frac{6}{19}$$
3. $$2\frac{3}{13}+2\frac{11}{13} = (2+2) + (\frac{3}{13} + \frac{11}{13}) = 4 + \frac{14}{13} = 4 + 1\frac{1}{13} = 5\frac{1}{13}$$
4. $$1\frac{5}{8}+3\frac{7}{8} = (1+3) + (\frac{5}{8} + \frac{7}{8}) = 4 + \frac{12}{8} = 4 + 1\frac{4}{8} = 4 + 1\frac{1}{2} = 5\frac{1}{2}$$
5. $$1-\frac{3}{11} = \frac{11}{11} - \frac{3}{11} = \frac{8}{11}$$
6. $$1-\frac{13}{40} = \frac{40}{40} - \frac{13}{40} = \frac{27}{40}$$
7. $$4-1\frac{1}{2} = 4 - \frac{3}{2} = \frac{8}{2} - \frac{3}{2} = \frac{5}{2} = 2\frac{1}{2}$$