Tính a) (1 1/4) . (-8/15) - 3/5 + 2/5 . (-3/4) b) (-0,125) . (-16) . (-8/9) . (-0,25)

* Hướng dẫn giải

a) 

$\begin{array}{l}\left(1\frac{1}{4}\right).\left(-\frac{8}{15}\right)-\frac{3}{5}+\frac{2}{5}.\left(-\frac{3}{4}\right)\\ =\left(\frac{5}{4}\right).\left(-\frac{8}{15}\right)-\frac{3}{5}-\frac{3}{10}\\ =\left(-\frac{2}{3}\right)-\frac{3}{5}-\frac{3}{10}\\ =-\frac{47}{30}\end{array}$

b)

$\begin{array}{l}\left(-0,125\right).(-16).\left(-\frac{8}{9}\right).\left(-0,25\right)\\ =\frac{1}{8}\mathrm{.16.}\frac{8}{9}.\frac{1}{4}=\frac{4}{9}\end{array}$