\(\left(\dfrac{-2}{3}+\dfrac{3}{7}\right):\dfrac{4}{5}+\left(\dfrac{-1}{3}+\dfrac{4}{7}\right):\dfrac{4}{5}\)
\(=\dfrac{4}{5}:\left[\left(\dfrac{-2}{3}+\dfrac{3}{7}\right)+\left(\dfrac{-1}{3}+\dfrac{4}{7}\right)\right]\)
\(=\dfrac{4}{5}:\left[\dfrac{-2}{3}+\dfrac{3}{7}+\dfrac{-1}{3}+\dfrac{4}{7}\right]\)
\(=\dfrac{4}{5}:\left[\left(\dfrac{3}{7}+\dfrac{4}{7}\right)+\left(\dfrac{-2}{3}+\dfrac{-1}{3}\right)\right]\)
\(=\dfrac{4}{5}:\left[\dfrac{7}{7}+\dfrac{-3}{3}\right]=\dfrac{4}{5}:\left[1+\left(-1\right)\right]=\dfrac{4}{5}:0=0\)
\(\left(-\dfrac{2}{3}+\dfrac{3}{7}\right):\dfrac{4}{5}+\left(-\dfrac{1}{3}+\dfrac{4}{7}\right):\dfrac{4}{5}\)
\(=\left[\left(-\dfrac{2}{3}\right)+\dfrac{3}{7}+\left(-\dfrac{1}{3}\right)+\dfrac{4}{7}\right]:\dfrac{4}{5}\)
\(=\left[\left(-\dfrac{2}{3}-\dfrac{1}{3}\right)+\left(\dfrac{3}{7}+\dfrac{4}{7}\right)\right]:\dfrac{4}{5}\)
\(\left[-1+1\right]:\dfrac{4}{5}\)
\(=0:\dfrac{4}{5}\)
\(=0\)