Вариант 1. Задание 2. Выполните действия: 1) $$\frac{1}{3} + \frac{2}{5}$$; 2) $$\frac{3}{5} - \frac{9}{20}$$; 3) $$3\frac{7}{8} + 2\frac{5}{12}$$; 4) $$7\frac{1}{10} - 5\frac{1}{6}$$.

1) $$\frac{1}{3} + \frac{2}{5} = \frac{5}{15} + \frac{6}{15} = \frac{11}{15}$$. 2) $$\frac{3}{5} - \frac{9}{20} = \frac{12}{20} - \frac{9}{20} = \frac{3}{20}$$. 3) $$3\frac{7}{8} + 2\frac{5}{12} = 3 + \frac{7}{8} + 2 + \frac{5}{12} = 5 + \frac{21}{24} + \frac{10}{24} = 5 + \frac{31}{24} = 5 + 1\frac{7}{24} = 6\frac{7}{24}$$. 4) $$7\frac{1}{10} - 5\frac{1}{6} = 7 + \frac{1}{10} - 5 - \frac{1}{6} = 2 + \frac{3}{30} - \frac{5}{30} = 2 - \frac{2}{30} = 2 - \frac{1}{15} = 1\frac{14}{15}$$.