Đáp án:
$\begin{array}{l}
a)\left( {\dfrac{1}{3} + \dfrac{{12}}{{67}} + \dfrac{{13}}{{41}}} \right) - \left( {\dfrac{{79}}{{67}} - \dfrac{{28}}{{41}}} \right)\\
= \dfrac{1}{3} + \left( {\dfrac{{12}}{{67}} - \dfrac{{79}}{{67}}} \right) + \dfrac{{13}}{{41}} + \dfrac{{28}}{{41}}\\
= \dfrac{1}{3} + \dfrac{{ - 67}}{{67}} + \dfrac{{41}}{{41}}\\
= \dfrac{1}{3} - 1 + 1\\
= \dfrac{1}{3}\\
b)1\dfrac{5}{{13}} - 0,\left( 3 \right) - \left( {1\dfrac{4}{9} + \dfrac{{18}}{{13}} - \dfrac{1}{3}} \right)\\
= 1 + \dfrac{5}{{13}} - \dfrac{1}{3} - 1 - \dfrac{4}{9} - \dfrac{{18}}{{13}} + \dfrac{1}{3}\\
= \left( {1 - 1} \right) + \left( {\dfrac{5}{{13}} - \dfrac{{18}}{{13}}} \right) + \left( {\dfrac{{ - 1}}{3} + \dfrac{1}{3}} \right) - \dfrac{4}{9}\\
= - 1 - 1 - \dfrac{4}{9}\\
= - 2 - \dfrac{4}{9} = \dfrac{{ - 22}}{9}\\
c)139\dfrac{5}{7}:\dfrac{2}{3} - 138\dfrac{2}{7}:\sqrt {\dfrac{4}{9}} \\
= \left( {139\dfrac{5}{7}} \right):\dfrac{2}{3} - 138\dfrac{2}{7}:\dfrac{2}{3}\\
= \left( {139\dfrac{5}{7} - 138\dfrac{2}{7}} \right):\dfrac{2}{3}\\
= \left( {139 + \dfrac{5}{7} - 138 - \dfrac{2}{7}} \right):\dfrac{2}{3}\\
= \left( {1 - \dfrac{3}{7}} \right).\dfrac{3}{2}\\
= \dfrac{4}{7}.\dfrac{3}{2}\\
= \dfrac{6}{7}\\
d)\left( {\dfrac{{ - 5}}{{11}}:\dfrac{{13}}{8} - \dfrac{5}{{11}}:\dfrac{{13}}{5}} \right) + \dfrac{{ - 1}}{{33}}\\
= - \dfrac{5}{{11}}:\left( {\dfrac{{13}}{8} - \dfrac{{13}}{5}} \right) - \dfrac{1}{{33}}\\
= \dfrac{{ - 5}}{{11}}:\dfrac{{ - 39}}{{40}} - \dfrac{1}{{33}}\\
= \dfrac{5}{{11}}.\dfrac{{40}}{{39}} - \dfrac{1}{{33}}\\
= \dfrac{1}{{33}}.\left( {\dfrac{{200}}{{13}} - 1} \right)\\
= \dfrac{1}{{33}}.\dfrac{{187}}{{13}}\\
= \dfrac{{17}}{{39}}
\end{array}$
