Решите примеры на сложение обыкновенных дробей с разными знаменателями.

**Ответы для второго и третьего столбцов:** **Второй столбец:** 2) $\frac{4}{9} + \frac{2}{3} = \frac{4}{9} + \frac{6}{9} = \frac{10}{9} = 1\frac{1}{9}$ 3) $\frac{3}{8} + \frac{3}{4} = \frac{3}{8} + \frac{6}{8} = \frac{9}{8} = 1\frac{1}{8}$ 4) $\frac{4}{7} + \frac{5}{21} = \frac{12}{21} + \frac{5}{21} = \frac{17}{21}$ 5) $\frac{7}{12} + \frac{3}{4} = \frac{7}{12} + \frac{9}{12} = \frac{16}{12} = \frac{4}{3} = 1\frac{1}{3}$ 6) $\frac{8}{9} + \frac{2}{3} = \frac{8}{9} + \frac{6}{9} = \frac{14}{9} = 1\frac{5}{9}$ 7) $\frac{5}{5} + \frac{7}{15} = 1 + \frac{7}{15} = 1\frac{7}{15}$ 8) $\frac{2}{21} + \frac{7}{14} = \frac{4}{42} + \frac{21}{42} = \frac{25}{42}$ 9) $\frac{4}{18} + \frac{5}{27} = \frac{12}{54} + \frac{10}{54} = \frac{22}{54} = \frac{11}{27}$ 10) $\frac{3}{15} + \frac{9}{20} = \frac{12}{60} + \frac{27}{60} = \frac{39}{60} = \frac{13}{20}$ **Третий столбец:** 2) $\frac{5}{6} + \frac{11}{18} = \frac{15}{18} + \frac{11}{18} = \frac{26}{18} = \frac{13}{9} = 1\frac{4}{9}$ 3) $\frac{7}{11} + \frac{5}{33} = \frac{21}{33} + \frac{5}{33} = \frac{26}{33}$ 4) $\frac{8}{9} + \frac{5}{18} = \frac{16}{18} + \frac{5}{18} = \frac{21}{18} = \frac{7}{6} = 1\frac{1}{6}$ 5) $\frac{3}{5} + \frac{2}{15} = \frac{9}{15} + \frac{2}{15} = \frac{11}{15}$ 6) $\frac{8}{17} + \frac{1}{34} = \frac{16}{34} + \frac{1}{34} = \frac{17}{34} = \frac{1}{2}$ 7) $\frac{1}{4} + \frac{1}{6} = \frac{3}{12} + \frac{2}{12} = \frac{5}{12}$ 8) $\frac{5}{8} + \frac{1}{10} = \frac{25}{40} + \frac{4}{40} = \frac{29}{40}$ 9) $\frac{7}{9} + \frac{1}{6} = \frac{14}{18} + \frac{3}{18} = \frac{17}{18}$ 10) $\frac{2}{21} + \frac{3}{14} = \frac{4}{42} + \frac{9}{42} = \frac{13}{42}$