\documentclass{article}
\usepackage{amsmath, amssymb, mathtools, tikz, enumitem, fancyhdr, mleftright, wrapfig}
\usetikzlibrary{calc}
\usepackage[margin=1in]{geometry}

\usepackage{fontspec,xltxtra,xunicode}
\defaultfontfeatures{Mapping=tex-text}
\setromanfont[Mapping=tex-text]{Linux Libertine O}
\setsansfont[Scale=MatchLowercase,Mapping=tex-text]{Linux Libertine O}
\setmonofont[Scale=MatchLowercase]{Linux Libertine O}

\newfontfamily{\IPA}[Scale=1]{Linux Libertine O}

\def\class{CS70}
\def\header{HW #}
\def\first{Kyle}
\def\last{Tse}

\fancypagestyle{first}
{
	\fancyhf{}
	\setlength{\headsep}{\baselineskip}
	\lhead{\class{}}
	\chead{\header}
	\rhead{\last, \first}
	\cfoot{\thepage}
}

\thispagestyle{first}

%%%%%%%%%%%%Commands%%%%%%%%%%%%
\newcommand{\diff}[1]{\mathrm{d}#1}    % Upright differential
\newcommand{\paren}[1]{\mleft( #1 \mright)}
\newcommand{\zerospace}
{
	\setlength{\abovedisplayskip}{0pt}
	\setlength{\belowdisplayskip}{0pt}
	\setlength{\abovedisplayshortskip}{0pt}
	\setlength{\belowdisplayshortskip}{0pt}
}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%Environments%%%%%%%%%%
\newenvironment{Question}   % Problem environment
{
	\section
}{}
\newenvironment{Parts}
{
	\begin{enumerate}[leftmargin = *, align = left, label = {\alph*.}, topsep = 0pt]
}
{
	\end{enumerate}
}
\newenvironment{Part}{\item}{}
%%%%
\newenvironment{solution}    % Solution environment
{
	\begin{enumerate}[leftmargin=0in]
		\item[\bfseries{Solution}]
}
{
	\end{enumerate}
}
%%%%
\newenvironment{nospaceflalign*}    % No extra vertical space before flalign* environment
{
	\setlength{\abovedisplayskip}{-\baselineskip}
	\csname flalign*\endcsname
}
{
	\csname endflalign*\endcsname
}
%%%% MATH DEFINITIONS %%%%
\let\Pr\relax
\DeclareMathOperator{\Pr}{\mathbb{P}}
\DeclareMathOperator{\Z}{\mathbb{Z}}
\DeclareMathOperator{\E}{\mathbb{E}}
\DeclareMathOperator{\R}{\mathbb{R}}
\DeclareMathOperator{\D}{\mathrm{d}}
\DeclareMathOperator{\var}{var}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%Homework%%%%%%%%%%%%%
\begin{document}
	\section*{Sundry}

	Text \\
	\fbox{\begin{minipage}{6.4in}\textit{I certify that all solutions are entirely in my words and that I have not looked at another student's solutions. I have credited all external sources in this write up.}\hfill\vspace{0.75in}\end{minipage}}

\bigskip%%%%%%%%%%%%%%%%%%%%%%%%%

	\section{Section 1}

	\begin{solution}
		Solution
	\end{solution}

\hrule %%%%%%%%%%%%%%%%%%%%%%%%%

	\section{Section 2}

	\begin{solution}
		Solution
	\end{solution}

\hrule %%%%%%%%%%%%%%%%%%%%%%%%%

	\section{Section 3}

	\begin{solution}
		Solution
	\end{solution}

\hrule %%%%%%%%%%%%%%%%%%%%%%%%%

	\section{Section 4}

	\begin{solution}
		Solution
	\end{solution}

\hrule %%%%%%%%%%%%%%%%%%%%%%%%%

	\section{Section 5}

	\begin{solution}
		Solution
	\end{solution}

\hrule %%%%%%%%%%%%%%%%%%%%%%%%%

	\section{Section 6}

	\begin{solution}
		Solution
	\end{solution}

\hrule %%%%%%%%%%%%%%%%%%%%%%%%%

\end{document}