Thực hiện các phép tính sau:\(\begin{array}{l}a)\,\frac{{ - 7}}{{12}} + \frac{5}{6}\\b)\,\frac{{ - 3}}{7}.

* Hướng dẫn giải

a) \(\frac{{ - 7}}{{12}} + \frac{5}{6} = \frac{{ - 7}}{{12}} + \frac{{10}}{{12}} = \frac{{ - 7 + 10}}{{12}} = \frac{3}{{12}} = \frac{1}{4}\)

b) \(\frac{{ - 3}}{7}.\frac{2}{{11}} + \frac{{ - 3}}{7}.\frac{9}{{11}} + 1\frac{3}{7}\)

\(\begin{array}{l}
 = \frac{{ - 3}}{7}\left( {\frac{2}{{11}} + \frac{9}{{11}}} \right) + \frac{{10}}{7}\\
 = \frac{{ - 3}}{7}.\frac{{11}}{{11}} + \frac{{10}}{7}\\
 = \frac{{ - 3}}{7} + \frac{{10}}{7} = \frac{7}{7} = 1
\end{array}\)