Вычислите: а) 4/5 + 1/9 + 2/3; b) 7/9 - 3/5 + 1/3; в) 2/15 + (7/15 - 1/5).

a) \(\frac{4}{5} + \frac{1}{9} + \frac{2}{3} = \frac{36}{45} + \frac{5}{45} + \frac{30}{45} = \frac{71}{45} = 1\frac{26}{45}\) б) \(\frac{7}{9} - \frac{3}{5} + \frac{1}{3} = \frac{35}{45} - \frac{27}{45} + \frac{15}{45} = \frac{23}{45}\) в) \(\frac{2}{15} + (\frac{7}{15} - \frac{1}{5}) = \frac{2}{15} + (\frac{7}{15} - \frac{3}{15}) = \frac{2}{15} + \frac{4}{15} = \frac{6}{15} = \frac{2}{5}\)