Đáp án:
$a) \dfrac{3}{4} .\dfrac{12}{-5} . (-\dfrac{25}{6})$
$ = \dfrac{-3.12.(-25)}{4.(-5).6}$
$ = \dfrac{900}{-120}$
$ = -\dfrac{15}{2}$
$b) (-2) . \dfrac{-38}{21} . \dfrac{-7}{4} . (-\dfrac{3}{8})$
$ = \dfrac{-2.(-38).(-7).(-3)}{21.4.8}$
$ =\dfrac{1596}{672}$
$ =\dfrac{19}{8}$
$c) (\dfrac{11}{12} : \dfrac{33}{16}) . \dfrac{3}{5}$
$ = (\dfrac{11}{12} . \dfrac{16}{33}) . \dfrac{3}{5}$
$ = \dfrac{4}{9} . \dfrac{3}{5}$
$ = \dfrac{12}{45}$
$=\dfrac{4}{15}$
$d) \dfrac{7}{23} . [(-\dfrac{8}{6})-\dfrac{45}{18}]$
$= \dfrac{7}{23} . [(-\dfrac{24}{18}) - \dfrac{45}{18}]$
$=\dfrac{7}{23} . (-\dfrac{69}{18})$
$ = \dfrac{7.(-69)}{23.18}$
$ = \dfrac{-483}{414}$
$ =\dfrac{-7}{6}$
