Tính rồi rút gọn (nếu có) 2/3 +5/9

a) \(\frac{2}{3}\) +\(\frac{5}{9}\) = \(\frac{6}{9}\) + \(\frac{5}{9}\) = \(\frac{{11}}{9}\)

b) $\frac{3}{7}$ \( \times \) $\frac{14}{9}$  = \(\frac{{42}}{{63}}\) = \(\frac{2}{3}\)