\(a,\left(\dfrac{1}{5}+\dfrac{4}{5}\right)+\left(\dfrac{5}{9}+\dfrac{1}{9}+\dfrac{3}{9}\right)\\ =1+1=2\\ b,\left(\dfrac{1}{3}+\dfrac{4}{3}+\dfrac{2}{3}\right)+\left(\dfrac{1}{6}+\dfrac{2}{6}+\dfrac{5}{6}\right)\\ =\dfrac{7\times2}{3\times2}+\dfrac{8}{6}=\dfrac{14}{6}+\dfrac{8}{6}=\dfrac{22}{6}=\dfrac{11}{3}\)
