\(\left(\dfrac{2}{3}+\dfrac{3}{4}-\dfrac{1}{5}\right):\left(-\dfrac{1}{3}+\dfrac{1}{2}-\dfrac{4}{10}\right)\)
\(=\left(\dfrac{40}{60}+\dfrac{45}{60}-\dfrac{12}{60}\right):\left(-\dfrac{10}{30}+\dfrac{15}{30}-\dfrac{12}{30}\right)\)
\(=\dfrac{73}{60}:-\dfrac{7}{30}\)
\(=\dfrac{73}{60}.\dfrac{-30}{7}\)
\(=-\dfrac{73}{14}\)
\(\left(\dfrac{2}{3}+\dfrac{3}{4}+\dfrac{1}{5}\right):\left(\dfrac{-1}{3}+\dfrac{1}{2}-\dfrac{4}{10}\right)\)\(=\dfrac{97}{60}:\left(\dfrac{-7}{30}\right)=\dfrac{-97}{14}\)