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