А. Найди значение сумм: 1) 1/3 + 1/6; 2) 1/2 + 1/3; 3) 3/5 − 1/10; 4) 1/12 + 5/6; 5) 1/3 + 1/4; 6) 1/3 + 2/5; 7) 1/2 − 1/4; 8) 8/7 − 1; 9) 1/4 − 1/5; 10) 3/4 − 1/8; 11) 1/5 + 1/6; 12) 4/15 + 2/5; 13) 7/10 − 1/2; 14) 1/3 − 1/4.

Чтобы сложить или вычесть дроби с разными знаменателями, приведём их к общему знаменателю.

1. \(\frac{1}{3}+\frac{1}{6}=\frac{2}{6}+\frac{1}{6}=\frac{1}{2}\).
2. \(\frac{1}{2}+\frac{1}{3}=\frac{3}{6}+\frac{2}{6}=\frac{5}{6}\).
3. \(\frac{3}{5}-\frac{1}{10}=\frac{6}{10}-\frac{1}{10}=\frac{1}{2}\).
4. \(\frac{1}{12}+\frac{5}{6}=\frac{1}{12}+\frac{10}{12}=\frac{11}{12}\).
5. \(\frac{1}{3}+\frac{1}{4}=\frac{4}{12}+\frac{3}{12}=\frac{7}{12}\).
6. \(\frac{1}{3}+\frac{2}{5}=\frac{5}{15}+\frac{6}{15}=\frac{11}{15}\).
7. \(\frac{1}{2}-\frac{1}{4}=\frac{2}{4}-\frac{1}{4}=\frac{1}{4}\).
8. \(\frac{8}{7}-1=\frac{8}{7}-\frac{7}{7}=\frac{1}{7}\).
9. \(\frac{1}{4}-\frac{1}{5}=\frac{5}{20}-\frac{4}{20}=\frac{1}{20}\).
10. \(\frac{3}{4}-\frac{1}{8}=\frac{6}{8}-\frac{1}{8}=\frac{5}{8}\).
11. \(\frac{1}{5}+\frac{1}{6}=\frac{6}{30}+\frac{5}{30}=\frac{11}{30}\).
12. \(\frac{4}{15}+\frac{2}{5}=\frac{4}{15}+\frac{6}{15}=\frac{2}{3}\).
13. \(\frac{7}{10}-\frac{1}{2}=\frac{7}{10}-\frac{5}{10}=\frac{1}{5}\).
14. \(\frac{1}{3}-\frac{1}{4}=\frac{4}{12}-\frac{3}{12}=\frac{1}{12}\).

Ответ: 1) \(\frac{1}{2}\); 2) \(\frac{5}{6}\); 3) \(\frac{1}{2}\); 4) \(\frac{11}{12}\); 5) \(\frac{7}{12}\); 6) \(\frac{11}{15}\); 7) \(\frac{1}{4}\); 8) \(\frac{1}{7}\); 9) \(\frac{1}{20}\); 10) \(\frac{5}{8}\); 11) \(\frac{11}{30}\); 12) \(\frac{2}{3}\); 13) \(\frac{1}{5}\); 14) \(\frac{1}{12}\).