Вычислите: 1) 6 4/9 + 3 5/9; 2) 10 11/19 + 5 14/19; 3) 2 3/13 + 2 11/13; 4) 1 5/8 + 3 7/8; 5) 1 − 3/11; 6) 1 − 13/40; 7) 4 − 1 4/7.

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

Ответ: 1) 10; 2) 16 6/19; 3) 5 1/13; 4) 5 1/2; 5) 8/11; 6) 27/40; 7) 2 3/7.