[latex tip] pre-defined brackets

1. set up with \newcommand

\newcommand\rbrackets[1]{\left({#1}\right)}
\newcommand\sbrackets[1]{\left[{#1}\right]}
\newcommand\cbrackets[1]{\left\{{#1}\right\}}
\newcommand\abrackets[1]{\left\langle{#1}\right\rangle}

2. usage

\begin{equation}

\sbrackets{\rbrackets{\frac{a}{b}}\times \frac{\frac{c}{d}}{e}}

\end{equation}

3. result