№1. Вычислите: 1) 7/8 + 5/6; 2) 11/12 − 3/4; 3) 5/14 + 1/7; 4) 13/15 − 2/5.

1. Общий знаменатель — 24: \(\frac{7}{8}+\frac{5}{6}=\frac{21}{24}+\frac{20}{24}=\frac{41}{24}=1\frac{17}{24}\).
2. \(\frac{11}{12}-\frac{3}{4}=\frac{11}{12}-\frac{9}{12}=\frac{2}{12}=\frac{1}{6}\).
3. \(\frac{5}{14}+\frac{1}{7}=\frac{5}{14}+\frac{2}{14}=\frac{7}{14}=\frac{1}{2}\).
4. \(\frac{13}{15}-\frac{2}{5}=\frac{13}{15}-\frac{6}{15}=\frac{7}{15}\).

Ответ: 1) 1 17/24; 2) 1/6; 3) 1/2; 4) 7/15.