\documentstyle[ans]{article}
\pagestyle{empty}
\makeanswers\once
\emergencystretch10pt

% The following arcane code defines bkslsh to be a textmode
% backslash.  In \LaTeX, \backslash defines backslash for mathmode
% but it doesn't look right in text mode.
% This definition gives the right size backslash for any Computer
% Modern size.
{\catcode`|=0\catcode`\\=\other
|def|bsl{{|tt\}}
|catcode`\=0 \global\let\bkslsh=|bsl}

\def\cmd#1{{\tt\bkslsh #1}}

\begin{document}
\begin{center}{\LARGE\bf Example of Class Handout}\end{center}

\section*{Sample Problems}

Here are some sample exercises.  The answers are on
the back of the page.  (Or: The answers will be handed out
later.)
\medbreak

\exercises

\exera Prove that for any integer $n\geq 3$ there are no nonzero
integers $x$, $y$ and $z$ for which $x^n+y^n=z^n$.
\answer If I knew how to do \cmd{marginpar} in \LaTeX\ I would
have written it in the margin.  But that's the way the cookie
crumbles.

\exer An exercise without an answer.

\exera The very last exercise.
\answer The very last answer.

\pagebreak
\setcounter{page}{1}
\section*{Answers to the exercises}
\doanswers
\end{document}