\(\dfrac{6}{7}+\dfrac{5}{7}:5-\dfrac{8}{9}=\dfrac{6}{7}+\dfrac{5}{7}.\dfrac{1}{5}-\dfrac{8}{9}=\dfrac{6}{7}+\dfrac{5}{35}-\dfrac{8}{9}=\dfrac{30}{35}+\dfrac{5}{35}-\dfrac{8}{9}=\dfrac{35}{35}-\dfrac{8}{9}=1-\dfrac{8}{9}=\dfrac{9}{9}-\dfrac{8}{9}=\dfrac{1}{9}\)