\(=\dfrac{6}{7}.\left(\dfrac{8}{13}+\dfrac{9}{13}-\dfrac{4}{13}\right)\)
\(=\dfrac{6}{7}.1\)
\(=\dfrac{6}{7}\)
\(=\dfrac{6}{7}.\left(\dfrac{8}{13}+\dfrac{9}{13}-\dfrac{4}{13}\right)=\dfrac{6}{7}.\left(\dfrac{8+9-4}{13}\right)=\dfrac{6}{7}.\dfrac{13}{13}=\dfrac{6}{7}.1=\dfrac{6}{7}\)