Đáp án:
$\begin{array}{l}
a)5\dfrac{{27}}{5} + \dfrac{{27}}{{23}} + 0,5 - \dfrac{5}{{27}} + \dfrac{{16}}{{23}}\\
= 5 + \dfrac{{27}}{5} + \dfrac{1}{2} - \dfrac{5}{{27}} + \dfrac{{27}}{{23}} + \dfrac{{16}}{{23}}\\
= 5 + \dfrac{{27}}{5} + \dfrac{1}{2} - \dfrac{5}{{27}} + \dfrac{{43}}{{23}}\\
= 12,58\\
2)\dfrac{3}{8}.27\dfrac{1}{5} - 51\dfrac{1}{5}.\dfrac{3}{8} + 19\\
= \dfrac{3}{8}.\left( {27\dfrac{1}{5} - 51\dfrac{1}{5}} \right) + 19\\
= \dfrac{3}{8}.\left( { - 24\dfrac{1}{5}} \right) + 19\\
= \dfrac{3}{8}.\left( { - 24} \right) + \dfrac{3}{8}.\left( { - \dfrac{1}{5}} \right) + 19\\
= - \dfrac{3}{{40}} + 10\\
= \dfrac{{397}}{{40}}\\
3)25.{\left( {\dfrac{{ - 1}}{5}} \right)^3} + \dfrac{1}{5} - 2.{\left( { - \dfrac{1}{2}} \right)^2} - \dfrac{1}{2}\\
= - 25.\dfrac{1}{{{5^3}}} + \dfrac{1}{5} - 2.\dfrac{1}{4} - \dfrac{1}{2}\\
= - \dfrac{1}{5} + \dfrac{1}{5} - \dfrac{1}{2} - \dfrac{1}{2}\\
= - 1\\
4)35\dfrac{1}{6}:\left( {\dfrac{{ - 4}}{5}} \right) - 46\dfrac{1}{6}:\left( {\dfrac{{ - 4}}{5}} \right)\\
= \left( {35\dfrac{1}{6} - 46\dfrac{1}{6}} \right):\left( {\dfrac{{ - 4}}{5}} \right)\\
= - 11\dfrac{1}{6}.\dfrac{{ - 5}}{4}\\
= \dfrac{{67}}{6}.\dfrac{5}{4}\\
= \dfrac{{335}}{{24}}
\end{array}$
