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