$\begin{array}{l}
+ )\,\,\frac{{15}}{6} - \frac{7}{4} + 2 = \frac{5}{2} - \frac{7}{4} + 2 = \frac{{10}}{4} - \frac{7}{4} + \frac{8}{4} = \frac{3}{4} + \frac{8}{4} = \frac{{11}}{4}\\
+ )\,\,3 - \left[ {\frac{{13}}{8} + \frac{5}{{12}}} \right] = 3 - \left[ {\frac{{39}}{{24}} + \frac{{10}}{{24}}} \right] = 3 - \frac{{49}}{{24}}\\
\,\,\,\,\,\, = \frac{{72}}{{24}} - \frac{{49}}{{24}} = \frac{{23}}{{24}}
\end{array}$
