\(\dfrac{\dfrac{-6}{7}+\dfrac{6}{13}-\dfrac{6}{29}}{\dfrac{9}{7}-\dfrac{9}{13}+\dfrac{9}{29}}=\dfrac{\dfrac{-6}{7}+\dfrac{6}{13}-\dfrac{6}{29}}{-\left(\dfrac{-9}{7}+\dfrac{9}{13}-\dfrac{9}{29}\right)}=\dfrac{6}{7}.\dfrac{\dfrac{-1}{7}+\dfrac{1}{13}-\dfrac{1}{29}}{-\left(\dfrac{1}{7}+\dfrac{1}{13}-\dfrac{1}{29}\right)}=\dfrac{6}{7}.\left(-1\right)=\dfrac{-6}{7}\)