Đáp án:
$\begin{array}{l}
a)\dfrac{{211}}{6}:\left( { - \dfrac{4}{5}} \right) - \dfrac{{271}}{6}:\left( { - \dfrac{4}{5}} \right)\\
= \left( {\dfrac{{211}}{6} - \dfrac{{271}}{6}} \right):\left( { - \dfrac{4}{5}} \right)\\
= \dfrac{{ - 60}}{6}.\dfrac{{ - 5}}{4}\\
= 10.\dfrac{5}{4}\\
= \dfrac{{25}}{2}\\
b)\dfrac{3}{4} - \left[ {\left( { - \dfrac{5}{3}} \right) - \left( {\dfrac{1}{{12}} + \dfrac{2}{9}} \right)} \right]\\
= \dfrac{3}{4} - \left( {\dfrac{{ - 5}}{3} - \dfrac{1}{{12}} - \dfrac{2}{9}} \right)\\
= \dfrac{3}{4} + \dfrac{5}{3} + \dfrac{1}{{12}} + \dfrac{2}{9}\\
= \dfrac{{3.9 + 5.12 + 1.3 + 2.4}}{{36}}\\
= \dfrac{{27 + 60 + 3 + 8}}{{36}}\\
= \dfrac{{98}}{{36}}\\
= \dfrac{{49}}{{18}}\\
c) - 3,75.\left( { - 7,2} \right) + 2,8.3,75\\
= 3,75.\left( {7,2 + 2,8} \right)\\
= 3,75.10\\
= 37,5\\
d){2^3}.\left( {0,75 - \dfrac{1}{4}} \right):\left( {\dfrac{7}{2} - \dfrac{9}{4}} \right)\\
= 8.\left( {\dfrac{3}{4} - \dfrac{1}{4}} \right):\left( {\dfrac{{14}}{4} - \dfrac{9}{4}} \right)\\
= 8.\dfrac{1}{2}:\dfrac{5}{4}\\
= 4.\dfrac{4}{5}\\
= \dfrac{{16}}{5}\\
e)\left( {\dfrac{7}{2} + 0,25} \right) - \left( {\dfrac{1}{4} - 3,25 + \dfrac{1}{2}} \right)\\
= \dfrac{7}{2} + \dfrac{1}{4} - \dfrac{1}{4} + 3,25 - \dfrac{1}{2}\\
= \left( {\dfrac{7}{2} - \dfrac{1}{2}} \right) + 3,25\\
= 3 + 3,25\\
= 6,25
\end{array}$
