1. Вычислите: 1) 3/5 + 7/10; 2) 11/12 − 5/18; 3) −4/7 + 9/14; 4) 5/6 · 9/10; 5) 7/8 : 14/15.

1. \(\frac{3}{5}+\frac{7}{10}=\frac{6}{10}+\frac{7}{10}=\frac{13}{10}=1\frac{3}{10}\).
2. \(\frac{11}{12}-\frac{5}{18}=\frac{33}{36}-\frac{10}{36}=\frac{23}{36}\).
3. \(-\frac{4}{7}+\frac{9}{14}=-\frac{8}{14}+\frac{9}{14}=\frac{1}{14}\).
4. \(\frac{5}{6}\cdot\frac{9}{10}=\frac{45}{60}=\frac{3}{4}\).
5. \(\frac{7}{8}:\frac{14}{15}=\frac{7}{8}\cdot\frac{15}{14}=\frac{15}{16}\).

Ответ: 1) \(1\frac{3}{10}\); 2) \(\frac{23}{36}\); 3) \(\frac{1}{14}\); 4) \(\frac{3}{4}\); 5) \(\frac{15}{16}\).