Вычислите: a) $$\frac{1}{2} + \frac{1}{3}$$; б) $$\frac{1}{4} + \frac{2}{5}$$; в) $$\frac{2}{3} + \frac{1}{4}$$; г) $$\frac{3}{4} + \frac{2}{5}$$; д) $$\frac{5}{7} - \frac{1}{6}$$; е) $$\frac{3}{4} - \frac{1}{3}$$; ж) $$\frac{1}{8} + \frac{1}{4}$$; з) $$\frac{2}{3} - \frac{5}{9}$$; и) $$\frac{1}{2} - \frac{5}{12}$$

a) $$\frac{1}{2} + \frac{1}{3} = \frac{3}{6} + \frac{2}{6} = \frac{5}{6}$$ б) $$\frac{1}{4} + \frac{2}{5} = \frac{5}{20} + \frac{8}{20} = \frac{13}{20}$$ в) $$\frac{2}{3} + \frac{1}{4} = \frac{8}{12} + \frac{3}{12} = \frac{11}{12}$$ г) $$\frac{3}{4} + \frac{2}{5} = \frac{15}{20} + \frac{8}{20} = \frac{23}{20} = 1\frac{3}{20}$$ д) $$\frac{5}{7} - \frac{1}{6} = \frac{30}{42} - \frac{7}{42} = \frac{23}{42}$$ е) $$\frac{3}{4} - \frac{1}{3} = \frac{9}{12} - \frac{4}{12} = \frac{5}{12}$$ ж) $$\frac{1}{8} + \frac{1}{4} = \frac{1}{8} + \frac{2}{8} = \frac{3}{8}$$ з) $$\frac{2}{3} - \frac{5}{9} = \frac{6}{9} - \frac{5}{9} = \frac{1}{9}$$ и) $$\frac{1}{2} - \frac{5}{12} = \frac{6}{12} - \frac{5}{12} = \frac{1}{12}$$ Ответ: a) $$\frac{5}{6}$$, б) $$\frac{13}{20}$$, в) $$\frac{11}{12}$$, г) $$1\frac{3}{20}$$, д) $$\frac{23}{42}$$, е) $$\frac{5}{12}$$, ж) $$\frac{3}{8}$$, з) $$\frac{1}{9}$$, и) $$\frac{1}{12}$$