\(a,=\dfrac{17}{11}.\left(\dfrac{66-80}{55}\right)+\dfrac{26}{5}\\ =\dfrac{17}{11}.\dfrac{-14}{55}+\dfrac{26}{5}\\ =-\dfrac{238}{605}+\dfrac{26}{5}\\ =\dfrac{-238+26.605}{605}=\dfrac{2908}{605}\\ b,=\dfrac{39}{5}+\dfrac{9}{4}-\dfrac{9}{5}-\dfrac{5}{4}-\dfrac{6}{7}\\ =6+1-\dfrac{6}{7}\\ =7-\dfrac{6}{7}\\ =\dfrac{49-6}{7}\\ =\dfrac{43}{7}\)