% !TEX TS-program = XeLaTeX
% Commands for running this example:
% 	 xelatex mathtools-example
% End of Commands
\documentclass{article}
\pagestyle{empty}
\usepackage{mathtools}
\usepackage{xepersian}
\settextfont{Persian Modern}
\begin{document}
\[
a=\frac{
\splitfrac{xy + xy + xy + xy + xy + xy}
{+ xy + xy + xy + xy}
}
{z}
=\frac{
\splitdfrac{xy + xy + xy + xy + xy}
{+ xy + xy + xy + xy}
}
{z}
\]
\end{document}