\(\dfrac{-5}{6}\times\dfrac{4}{19}+\dfrac{-7}{12}\times\dfrac{4}{19}-\dfrac{40}{57}=\dfrac{4}{19}\times\left(\dfrac{-5}{6}+\dfrac{-7}{12}\right)-\dfrac{40}{57}=\dfrac{4}{19}\times\left(\dfrac{-10}{12}+\dfrac{-7}{12}\right)-\dfrac{40}{57}=\dfrac{4}{19}\times\dfrac{-17}{12}-\dfrac{40}{57}=\dfrac{-17}{57}-\dfrac{40}{57}=\dfrac{-57}{57}=-1\)