\documentclass[11pt]{report}
 \usepackage{xepersian}

 \settextfont[Scale=1]{Yas}
 \setlatintextfont{Junicode}


\setdigitfont[Scale=1]{Yas}
 \defpersianfont\nastaliq[Scale=2]{IranNastaliq}
  
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\textheight=22cm%تنظیم طول متن   
\textwidth=14.7cm%تنظیم عرض متن  
\topmargin=0cm%تنظیم حاشیه بالای صفحه 
\oddsidemargin=0cm%تنظیم حاشیه سمت چپ صفحه 
%\headsep=1cm%     فاصله متن از سر برگ   
\footskip=1cm% فاصله شماره صفحه از انتهای متن 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

 
 \begin{document}
 \baselineskip=1.5cm

 \pagenumbering{alph}


 
 $\dfrac{4}{5}$    و      $\frac{1}{2}$  و    $\tfrac{2}{3}$
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%


$$ \iint  f(x,y)dxdy=\iiint f$$
$$\int\int g(x,y)dxdy \int\int\int g$$
 %%%%%%%%%%%%%%%%%%%%
 
 % از فایل پی دی اف mathmode
 \begin{multline}
 A = \lim _{n\rightarrow \infty }\Delta x\left( a^{2}+\left( a^{2}+2a\Delta x
 +\left( \Delta x\right) ^{2}\right)\right.\\
+\left( a^{2}+2\cdot 2a\Delta x+2^{2}\left( \Delta x\right) ^{2}\right)\\
 +\left( a^{2}+2\cdot 3a\Delta x+3^{2}\left( \Delta x\right) ^{2}\right)\\
 + \ldots\\
 \left.+\left( a^{2}+2\cdot (n-1)a\Delta x +(n-1)^{2}\left( \Delta x\right) ^{2}\right) \right)\\
 = \frac{1}{3}\left( b^{3}-a^{3}\right)
 \end{multline}
 
 \end{document}\lr{•}