Thực hiện các phép tính: \(B = \left( {1\dfrac{5}{{12}} + 3.\dfrac{7}{{36}}} \right):\left( { - \dfrac{2}{{2019}}} \right)\)

* Hướng dẫn giải

\(\begin{array}{l}B = \left( {1\dfrac{5}{{12}} + 3.\dfrac{7}{{36}}} \right):\left( { - \dfrac{2}{{2019}}} \right)\\\,\,\,\,\, = \left( {\dfrac{{17}}{{12}} + \dfrac{{3.7}}{{36}}} \right):\left( {\dfrac{{ - 2}}{{2019}}} \right)\\\,\,\,\,\, = \left( {\dfrac{{17}}{{12}} + \dfrac{7}{{12}}} \right).\dfrac{{2019}}{{ - 2}}\\\,\,\,\, = \dfrac{{24}}{{12}}.\dfrac{{2019}}{{ - 2}}\\\,\,\,\, = 2.\dfrac{{2019}}{{ - 2}}\\\,\,\,\, =  - 2019\end{array}\)