\(\dfrac{2}{3}+\left(\dfrac{5}{14}+\dfrac{-25}{23}\right)-\left(\dfrac{-2}{23}-\dfrac{9}{14}\right)=\dfrac{2}{3}+\dfrac{5}{14}-\dfrac{25}{23}-\dfrac{2}{23}+\dfrac{9}{14}=\left(\dfrac{5}{14}+\dfrac{9}{14}\right)+\left(-\dfrac{25}{23}+\dfrac{2}{23}\right)+\dfrac{2}{3}=1-1+\dfrac{2}{3}=\dfrac{2}{3}\)