\documentclass[12pt,twoside]{bidipresentation}
\usepackage{xepersian}
\settextfont[Scale=1.37]{XB Niloofar}
\setlatintextfont[Scale=1]{Times New Roman}
\pagestyle{pres}
\usepackage[pagebackref=true,colorlinks=true,linkcolor=blue,citecolor=magenta]{hyperref}
  \usepackage{xcolor, color} 

\usepackage{amssymb,amsmath}
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\begin{document}
\begin{plainslide}
$$\pounds(e^{at})=\int e^{-st}e^{at}dt$$
\end{plainslide}
\end{document}