Bài tập về phép chia và phối hợp bốn phép tính

5. 

a) $A = \frac{11}{12}:\left ( \frac{7}{9}+\frac{-16}{17} \right )-\left ( \frac{2}{3}-\frac{5}{15} \right )$

    = $\frac{11}{12}: \frac{-25}{153}-\frac{1}{3}$

    = $\frac{11}{12}.\frac{-153}{25}-\frac{1}{3}$

    = $\frac{-561}{100}-\frac{1}{3}$

    = $\frac{-1783}{300}$

b) $B = \frac{-1}{5}.\left ( \frac{9}{8}+\frac{16}{32}-\frac{12}{46} \right )-\frac{9}{17}$

    = $\frac{-1}{5}.\frac{251}{184}-\frac{9}{17}$

    = $\frac{-251}{920}-\frac{9}{17}$

    = $\frac{-12547}{15640}$

6. 

a) $\frac{5}{14}.\frac{1}{3}.\frac{-4}{15}:\frac{5}{7}$

   = $\frac{5}{14}.\frac{1}{3}.\frac{-4}{15}.\frac{7}{5}$

   = $\frac{-2}{15}$

b) $\left [ \frac{-8}{13}-\left ( \frac{2}{5}+\frac{1}{13}-\frac{2}{10} \right ) \right ]:\frac{58}{65}$

   = $\left ( \frac{-8}{13}-\frac{18}{65} \right ).\frac{65}{58}$

   = $\frac{-58}{65}.\frac{65}{58}$

   = -1