\(\dfrac{\left(\dfrac{2}{3}\right)^3.\left(-\dfrac{3}{4}\right)^2.\left(-1\right)^5}{\left(\dfrac{2}{5}\right)^2.\left(-\dfrac{5}{12}\right)^2}\)
\(=\dfrac{\dfrac{8}{27}.\dfrac{9}{16}.\left(-1\right)}{\left(\dfrac{2}{5}.-\dfrac{5}{12}\right)^2}\)
\(=\dfrac{\dfrac{1}{3}.\dfrac{1}{2}.\left(-1\right)}{\left(-\dfrac{1}{6}\right)^2}=\dfrac{-\dfrac{1}{6}}{\dfrac{1}{36}}=-6\)