Вариант 1. Вычислите: 11) 1/2 + 3/4; 12) 6/7 + 5/14; 13) 2/3 + 7/12; 14) 4/5 + 3/20; 15) 4/9 + 7/18; 16) 9/10 + 4/15; 17) 5/6 + 3/14; 18) 5/12 + 1/18; 19) 1/8 + 3/12; 20) 3/4 + 1/6.

Приводим дроби к общему знаменателю и складываем числители.

1. \(\frac{1}{2}+\frac{3}{4}=\frac{2}{4}+\frac{3}{4}=\frac{5}{4}=1\frac{1}{4}\).
2. \(\frac{6}{7}+\frac{5}{14}=\frac{12}{14}+\frac{5}{14}=\frac{17}{14}=1\frac{3}{14}\).
3. \(\frac{2}{3}+\frac{7}{12}=\frac{8}{12}+\frac{7}{12}=\frac{15}{12}=1\frac{1}{4}\).
4. \(\frac{4}{5}+\frac{3}{20}=\frac{16}{20}+\frac{3}{20}=\frac{19}{20}\).
5. \(\frac{4}{9}+\frac{7}{18}=\frac{8}{18}+\frac{7}{18}=\frac{15}{18}=\frac{5}{6}\).
6. \(\frac{9}{10}+\frac{4}{15}=\frac{27}{30}+\frac{8}{30}=\frac{35}{30}=1\frac{1}{6}\).
7. \(\frac{5}{6}+\frac{3}{14}=\frac{35}{42}+\frac{9}{42}=\frac{44}{42}=1\frac{1}{21}\).
8. \(\frac{5}{12}+\frac{1}{18}=\frac{15}{36}+\frac{2}{36}=\frac{17}{36}\).
9. \(\frac{1}{8}+\frac{3}{12}=\frac{3}{24}+\frac{6}{24}=\frac{9}{24}=\frac{3}{8}\).
10. \(\frac{3}{4}+\frac{1}{6}=\frac{9}{12}+\frac{2}{12}=\frac{11}{12}\).