\documentclass[12pt]{letter}

\usepackage[T1]{fontenc}
\usepackage{textcomp}
\renewcommand{\rmdefault}{ugm}
\renewcommand{\sfdefault}{phv}
\usepackage[garamond]{mathdesign}

\usepackage[letterpaper,left=1.3in,right=1.3in,top=0.8in,bottom=0.8in]{geometry}

\begin{document}

\begin{letter}{Person Letter is Addressed To\\
Followed by Address}

\address{Benjamin Mako Hill\\
Massachusetts Institute of Technology\\
Room E15-312\\
20 Ames Street\\
Cambridge, MA 02139-4307}

\signature{Benjamin Mako Hill}

\location{Massachusetts Institute of Technology\\
Room E15-020c\\
20 Ames Street\\
Cambridge, MA 02139-4307}

\telephone{(206) 409-7191} 

\opening{To whom it may concern,}
\setlength\parindent{0.25in}

Text of Letter goes here. Text of Letter goes here. Text of Letter
goes here. Text of Letter goes here. Text of Letter goes here. Text of
Letter goes here. Text of Letter goes here. Text of Letter goes
here. Text of Letter goes here.

\closing{Regards,}

\end{letter}

\end{document}