\(\dfrac{2}{5}\times\dfrac{3}{4}\times\dfrac{5}{6}:\dfrac{3}{4}\)
\(=\dfrac{2}{5}\times\dfrac{3}{4}\times\dfrac{5}{6}\times\dfrac{4}{3}\)
\(=\left(\dfrac{2}{5}\times\dfrac{5}{6}\right)\times\left(\dfrac{3}{4}\times\dfrac{4}{3}\right)\)
\(=\dfrac{2}{6}\times1\)
\(=\dfrac{1}{3}\)