\(a:=\left(\dfrac{3}{5}+\dfrac{2}{5}\right)+\left(\dfrac{4}{7}+\dfrac{2}{7}+\dfrac{1}{7}\right)\\ =1+1=2\\ b:=\left(\dfrac{1}{5}+\dfrac{9}{5}\right)+\left(\dfrac{2}{5}+\dfrac{8}{5}\right)+\left(\dfrac{3}{5}+\dfrac{7}{5}\right)+\left(\dfrac{4}{5}+\dfrac{6}{5}\right)\\ =2+2+2+2=8\)
