1 вариант: 1) 1/2 + 2/3; 2) 3 − 4/5; 3) 3 1/3 + 5 3/4; 4) 6 1/2 − 2 2/3; 5) 1/2 × 2/3; 6) 2 2/15 × 1 3/16; 7) 4/15 : 12/35; 8) 9 : 1 4/5.

1. Приведём дроби к общему знаменателю: \(\frac{1}{2}+\frac{2}{3}=\frac{3}{6}+\frac{4}{6}=\frac{7}{6}=1\frac{1}{6}\).
2. \(3-\frac{4}{5}=2\frac{5}{5}-\frac{4}{5}=2\frac{1}{5}\).
3. \(3\frac{1}{3}+5\frac{3}{4}=8+\frac{1}{3}+\frac{3}{4}=8+\frac{4}{12}+\frac{9}{12}=8\frac{13}{12}=9\frac{1}{12}\).
4. \(6\frac{1}{2}-2\frac{2}{3}=6\frac{3}{6}-2\frac{4}{6}=3\frac{5}{6}\).
5. \(\frac{1}{2}\times\frac{2}{3}=\frac{2}{6}=\frac{1}{3}\).
6. \(2\frac{2}{15}\times1\frac{3}{16}=\frac{32}{15}\times\frac{19}{16}=\frac{2\times19}{15}=\frac{38}{15}=2\frac{8}{15}\).
7. \(\frac{4}{15}:\frac{12}{35}=\frac{4}{15}\times\frac{35}{12}=\frac{7}{9}\).
8. \(9:1\frac{4}{5}=9:\frac{9}{5}=9\times\frac{5}{9}=5\).

Ответ: 1) \(1\frac{1}{6}\); 2) \(2\frac{1}{5}\); 3) \(9\frac{1}{12}\); 4) \(3\frac{5}{6}\); 5) \(\frac{1}{3}\); 6) \(2\frac{8}{15}\); 7) \(\frac{7}{9}\); 8) \(5\).