Вычислите: a) $$\frac{1}{3} + (-\frac{2}{7}) =$$ b) $$\frac{4}{9} + \frac{2}{3} =$$ v) $$\frac{5}{12} - \frac{7}{9} =$$ g) $$\frac{8}{15} + (-\frac{7}{10}) =$$

Выполним вычисления: a) $$\frac{1}{3} + (-\frac{2}{7}) = \frac{1}{3} - \frac{2}{7} = \frac{7}{21} - \frac{6}{21} = \frac{1}{21}$$ б) $$\frac{4}{9} + \frac{2}{3} = \frac{4}{9} + \frac{6}{9} = \frac{10}{9} = 1\frac{1}{9}$$ в) $$\frac{5}{12} - \frac{7}{9} = \frac{15}{36} - \frac{28}{36} = -\frac{13}{36}$$ г) $$\frac{8}{15} + (-\frac{7}{10}) = \frac{8}{15} - \frac{7}{10} = \frac{16}{30} - \frac{21}{30} = -\frac{5}{30} = -\frac{1}{6}$$