Tính:
a) \(\dfrac{-3}{4}.\dfrac{12}{-5}.\left(-\dfrac{25}{6}\right);\) b) \(\left(-2\right).\dfrac{-38}{21}.\dfrac{-7}{4}.\left(-\dfrac{3}{8}\right);\)
c) \(\left(\dfrac{11}{12}:\dfrac{33}{16}\right).\dfrac{3}{5};\) d) \(\dfrac{7}{23}.\left[\left(-\dfrac{8}{6}\right)-\dfrac{45}{18}\right].\)