Вычислите: а) 4/13 + 3/13; б) 7/11 − 1/11; в) 4 3/9 + 2 1/9; г) 8 4/5 − 7 2/5; д) 3 9/16 + 2 3/16; е) 5 6/13 − 3 1/13; ж) 9/22 · 11/27; з) 4/27 : 20/81.

1. \(\frac{4}{13}+\frac{3}{13}=\frac{4+3}{13}=\frac{7}{13}\).
2. \(\frac{7}{11}-\frac{1}{11}=\frac{7-1}{11}=\frac{6}{11}\).
3. \(4\frac{3}{9}+2\frac{1}{9}=6\frac{3+1}{9}=6\frac{4}{9}\).
4. \(8\frac{4}{5}-7\frac{2}{5}=1\frac{4-2}{5}=1\frac{2}{5}\).
5. \(3\frac{9}{16}+2\frac{3}{16}=5\frac{12}{16}=5\frac{3}{4}\).
6. \(5\frac{6}{13}-3\frac{1}{13}=2\frac{5}{13}\).
7. \(\frac{9}{22}\cdot\frac{11}{27}=\frac{1}{2}\cdot\frac{1}{3}=\frac{1}{6}\).
8. \(\frac{4}{27}:\frac{20}{81}=\frac{4}{27}\cdot\frac{81}{20}=\frac{3}{5}\).

Ответ: а) \(\frac{7}{13}\); б) \(\frac{6}{11}\); в) \(6\frac{4}{9}\); г) \(1\frac{2}{5}\); д) \(5\frac{3}{4}\); е) \(2\frac{5}{13}\); ж) \(\frac{1}{6}\); з) \(\frac{3}{5}\).