\documentclass[12pt]{article}

\title{Bopytex with Mapytex example -- \Var{ subject.number }}

% solution/print = false

\begin{document}

\maketitle

%- set e = Expression.random("{a} + {b}")
\Var{e}

\Var{e.simplify()}

\section{Variables}
\subsection{subject}
\Var{subject}
\subsection{options}
\Var{options}

\end{document}