\usepackage{lastpage}
\usepackage{fancyhdr}
	\pagestyle{fancy}
	\fancyfoot[C]{\fcolorbox{black}{gray!20}{\thepage~/~\pageref{LastPage}}}
	\renewcommand{\headrulewidth}{0pt}
	\renewcommand{\footrulewidth}{0pt}
	\pagestyle{fancy}