Вычислите: 1) $$\frac{3}{4} + \frac{5}{7}$$; 2) $$8\frac{6}{35} - 6\frac{7}{10}$$; 3) $$\frac{19}{24} - \frac{25}{36}$$; 4) $$7\frac{8}{15} + 8\frac{17}{20}$$; 5) $$\frac{11}{18} - \frac{5}{12}$$; 6) $$\frac{5}{6} - \frac{3}{4} + \frac{5}{24}$$.

1) $$\frac{3}{4} + \frac{5}{7} = \frac{3 \cdot 7}{4 \cdot 7} + \frac{5 \cdot 4}{7 \cdot 4} = \frac{21}{28} + \frac{20}{28} = \frac{21 + 20}{28} = \frac{41}{28} = 1\frac{13}{28}$$. 2) $$8\frac{6}{35} - 6\frac{7}{10} = 8\frac{12}{70} - 6\frac{49}{70} = 7\frac{82}{70} - 6\frac{49}{70} = (7 - 6) + (\frac{82}{70} - \frac{49}{70}) = 1 + \frac{82 - 49}{70} = 1 + \frac{33}{70} = 1\frac{33}{70}$$. 3) $$\frac{19}{24} - \frac{25}{36} = \frac{19 \cdot 3}{24 \cdot 3} - \frac{25 \cdot 2}{36 \cdot 2} = \frac{57}{72} - \frac{50}{72} = \frac{57 - 50}{72} = \frac{7}{72}$$. 4) $$7\frac{8}{15} + 8\frac{17}{20} = 7\frac{32}{60} + 8\frac{51}{60} = (7 + 8) + (\frac{32}{60} + \frac{51}{60}) = 15 + \frac{32 + 51}{60} = 15 + \frac{83}{60} = 15 + 1\frac{23}{60} = 16\frac{23}{60}$$. 5) $$\frac{11}{18} - \frac{5}{12} = \frac{11 \cdot 2}{18 \cdot 2} - \frac{5 \cdot 3}{12 \cdot 3} = \frac{22}{36} - \frac{15}{36} = \frac{22 - 15}{36} = \frac{7}{36}$$. 6) $$\frac{5}{6} - \frac{3}{4} + \frac{5}{24} = \frac{5 \cdot 4}{6 \cdot 4} - \frac{3 \cdot 6}{4 \cdot 6} + \frac{5}{24} = \frac{20}{24} - \frac{18}{24} + \frac{5}{24} = \frac{20 - 18 + 5}{24} = \frac{7}{24}$$.