Thực hiện phép tính $\dfrac{2}{9}.\left[ {\dfrac{{ - 4}}{{45}}:\left( {\dfrac{1}{5} - \dfrac{2}{{15}}} \right) + 1\dfrac{2}{3}} \right] - \left( {\dfrac{{ - 5}}{{27}}} \right)$ ta được kết quả là

Ta có $\dfrac{2}{9}.\left[ {\dfrac{{ - 4}}{{45}}:\left( {\dfrac{1}{5} - \dfrac{2}{{15}}} \right) + 1\dfrac{2}{3}} \right] - \left( {\dfrac{{ - 5}}{{27}}} \right)$

$= \dfrac{2}{9}.\left[ {\dfrac{{ - 4}}{{45}}:\left( {\dfrac{3}{{15}} - \dfrac{2}{{15}}} \right) + \dfrac{5}{3}} \right] - \left( {\dfrac{{ - 5}}{{27}}} \right)$

$= \dfrac{2}{9}.\left[ {\dfrac{{ - 4}}{{45}}:\dfrac{1}{{15}} + \dfrac{5}{3}} \right] - \left( {\dfrac{{ - 5}}{{27}}} \right)$

$= \dfrac{2}{9}.\left[ {\dfrac{{ - 4}}{{45}}.\dfrac{{15}}{1} + \dfrac{5}{3}} \right] - \left( {\dfrac{{ - 5}}{{27}}} \right)$

$= \dfrac{2}{9}.\left[ {\dfrac{{ - 4}}{3} + \dfrac{5}{3}} \right] - \left( {\dfrac{{ - 5}}{{27}}} \right)$

$= \dfrac{2}{9}.\dfrac{1}{3} - \left( {\dfrac{{ - 5}}{{27}}} \right)$

$= \dfrac{2}{{27}} + \dfrac{5}{{27}}$

$= \dfrac{7}{{27}}$