Вычислите и запишите ответ: 1) 1/9 + 1/27; 2) 38/49 − 3/7; 3) 2/3 + 1/9; 4) 7/8 + 1/2; 5) 5/7 − 1/2; 6) 5/6 − 3/5; 7) 1/9 − 1/27; 8) 8/9 − 2/7; 9) 7/8 − 1/2; 10) 5/26 + 1/6; 11) 1/10 − 1/11; 12) 1/3 + 1/7; 13) 2/7 + 7/9; 14) 1/2 + 1/8; 15) 3/5 + 5/6; 16) 1/2 − 1/8; 17) 1/12 + 1/3; 18) 8/9 − 7/8

1. \(\frac{1}{9}+\frac{1}{27}=\frac{3}{27}+\frac{1}{27}=\frac{4}{27}\).
2. \(\frac{38}{49}-\frac{3}{7}=\frac{38}{49}-\frac{21}{49}=\frac{17}{49}\).
3. \(\frac{2}{3}+\frac{1}{9}=\frac{6}{9}+\frac{1}{9}=\frac{7}{9}\).
4. \(\frac{7}{8}+\frac{1}{2}=\frac{7}{8}+\frac{4}{8}=\frac{11}{8}=1\frac{3}{8}\).
5. \(\frac{5}{7}-\frac{1}{2}=\frac{10}{14}-\frac{7}{14}=\frac{3}{14}\).
6. \(\frac{5}{6}-\frac{3}{5}=\frac{25}{30}-\frac{18}{30}=\frac{7}{30}\).
7. \(\frac{1}{9}-\frac{1}{27}=\frac{3}{27}-\frac{1}{27}=\frac{2}{27}\).
8. \(\frac{8}{9}-\frac{2}{7}=\frac{56}{63}-\frac{18}{63}=\frac{38}{63}\).
9. \(\frac{7}{8}-\frac{1}{2}=\frac{7}{8}-\frac{4}{8}=\frac{3}{8}\).
10. \(\frac{5}{26}+\frac{1}{6}=\frac{15}{78}+\frac{13}{78}=\frac{28}{78}=\frac{14}{39}\).
11. \(\frac{1}{10}-\frac{1}{11}=\frac{11}{110}-\frac{10}{110}=\frac{1}{110}\).
12. \(\frac{1}{3}+\frac{1}{7}=\frac{7}{21}+\frac{3}{21}=\frac{10}{21}\).
13. \(\frac{2}{7}+\frac{7}{9}=\frac{18}{63}+\frac{49}{63}=\frac{67}{63}=1\frac{4}{63}\).
14. \(\frac{1}{2}+\frac{1}{8}=\frac{4}{8}+\frac{1}{8}=\frac{5}{8}\).
15. \(\frac{3}{5}+\frac{5}{6}=\frac{18}{30}+\frac{25}{30}=\frac{43}{30}=1\frac{13}{30}\).
16. \(\frac{1}{2}-\frac{1}{8}=\frac{4}{8}-\frac{1}{8}=\frac{3}{8}\).
17. \(\frac{1}{12}+\frac{1}{3}=\frac{1}{12}+\frac{4}{12}=\frac{5}{12}\).
18. \(\frac{8}{9}-\frac{7}{8}=\frac{64}{72}-\frac{63}{72}=\frac{1}{72}\).

Ответы: \(\frac{4}{27};\ \frac{17}{49};\ \frac{7}{9};\ 1\frac{3}{8};\ \frac{3}{14};\ \frac{7}{30};\ \frac{2}{27};\ \frac{38}{63};\ \frac{3}{8};\ \frac{14}{39};\ \frac{1}{110};\ \frac{10}{21};\ 1\frac{4}{63};\ \frac{5}{8};\ 1\frac{13}{30};\ \frac{3}{8};\ \frac{5}{12};\ \frac{1}{72}\).