1. Вычислите: а) 3/4 + 1/8; б) 11/15 − 7/20; в) 5/4 · 2/3; г) 3/20 : 9/10; д) 2 2/5 + 3 1/6; е) 5 2/3 − 2 3/4; ж) 4 2/15 · 5; з) 7 3/5 : 19.

1. а) \(\frac{3}{4}+\frac{1}{8}=\frac{6}{8}+\frac{1}{8}=\frac{7}{8}\).
2. б) \(\frac{11}{15}-\frac{7}{20}=\frac{44}{60}-\frac{21}{60}=\frac{23}{60}\).
3. в) \(\frac{5}{4}\cdot\frac{2}{3}=\frac{10}{12}=\frac{5}{6}\).
4. г) \(\frac{3}{20}:\frac{9}{10}=\frac{3}{20}\cdot\frac{10}{9}=\frac{1}{6}\).
5. д) \(2\frac{2}{5}+3\frac{1}{6}=\frac{12}{5}+\frac{19}{6}=\frac{72}{30}+\frac{95}{30}=\frac{167}{30}=5\frac{17}{30}\).
6. е) \(5\frac{2}{3}-2\frac{3}{4}=\frac{17}{3}-\frac{11}{4}=\frac{68}{12}-\frac{33}{12}=\frac{35}{12}=2\frac{11}{12}\).
7. ж) \(4\frac{2}{15}\cdot5=\frac{62}{15}\cdot5=\frac{62}{3}=20\frac{2}{3}\).
8. з) \(7\frac{3}{5}:19=\frac{38}{5}:19=\frac{38}{5}\cdot\frac{1}{19}=\frac{2}{5}\).

Ответ: а) 7/8; б) 23/60; в) 5/6; г) 1/6; д) 5 17/30; е) 2 11/12; ж) 20 2/3; з) 2/5.