\documentclass[11pt]{exam}
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%  Created by Nancy Ide on 2008-12-10.
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\usepackage{enumerate}

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\header{CS240\\Assignment 1}{}{YOUR NAME\\ \thepage \ of \numpages}

\begin{document}

% Questions start here:
\begin{questions}

\question
Here is a question about a string $x$ with length $n \ge 0$.

\noindent
{\bf Answer:}

My answer appears here.

\question
Here is a question about FAs recognizing the following languages over $\Sigma = (a,b)$.
\begin{enumerate} [a.]
\item $\{w | w $ contains at least three $a$Ős\}.
\item $\{w | w $ starts with an $a$ and has odd length\}.
\end{enumerate}

\noindent
{\bf Answer:}

\begin{enumerate} [a.]
\item My answer to part (a) appears here.

\item My answer to part (b) appears here.
\end{enumerate}

\end{questions}
\end{document}