Tính: a) 5,75.-8/9 b) 2 3/8.(-0,4) c) -12/5: (-6,5)

* Hướng dẫn giải

$$\begin{gathered} a) 5,75.\frac{-8}{9}=\frac{575}{100}.\frac{-8}{9} \\ =\frac{23}{4}.\frac{-8}{9}=\frac{-46}{9} \\ b) 2\frac{3}{8}.(-0,4)=\frac{19}{8}.\frac{-4}{10} \\ =\frac{19}{8}.\frac{-2}{5}=\frac{-19}{20} \\ c) \frac{{\displaystyle -12}}{{\displaystyle 5}}:(-6,5)=\frac{{\displaystyle -12}}{{\displaystyle 5}}:\frac{{\displaystyle -65}}{{\displaystyle 10}} \\ =\frac{{\displaystyle 12}}{{\displaystyle 5}}:\frac{{\displaystyle 13}}{{\displaystyle 2}}=\frac{{\displaystyle 12}}{{\displaystyle 5}}.\frac{{\displaystyle 2}}{{\displaystyle 13}}=\frac{{\displaystyle 24}}{{\displaystyle 65}} \end{gathered}$$