\documentclass[letterpaper,12pt]{article}
\usepackage{fullpage}
\usepackage{amssymb}
\usepackage{hyperref}

% TODO: FILL IN NAME, ID, AND COLLABORATORS HERE.
% List your collaborators for all problems in Homework 1.

\def\name{YOUR NAME HERE}
\def\id{YOUR ID HERE}
\def\collabs{YOUR COLLABORATORS HERE, SEPARATED BY COMMAS.}
% END PART TO FILL IN

\newtheorem{theorem}{Theorem}
\newenvironment{proof}{\emph{Proof:}}{\hfill $\Box$}

\begin{document}

\newlength{\boxwidth}
\setlength{\boxwidth}{\textwidth}
\addtolength{\boxwidth}{-2cm}
\noindent\framebox[\textwidth]{\hfil
\parbox[t]{\boxwidth}{%
{\bfseries CSE\,105: Automata and Computability Theory \hfill Winter 2015}
\begin{center}\huge Homework \#1 Solutions\end{center}
\name\hfill\id%
}\hfil}
\vspace{0.7cm}

\noindent\textbf{Collaborated with:} \collabs
\bigskip


\noindent\textbf{Solution to Problem 2}

\begin{theorem}
  For any positive integer $n$,
  \[ \sum_{k=1}^n (2k) = n^2 + n. \]
\end{theorem}
\begin{proof}

% PROBLEM 2 SOLUTION GOES HERE

\end{proof}


\end{document}