[OS X TeX] \newcommand\eal{\end{align}

[David Arnold]

All,

A colleague of mine asked why this won't compile.

\documentclass[12pt]{article}
\usepackage{amsmath,amssymb}

\newcommand{\bal}{\begin{align*}}
\newcommand{\eal}{\end{align*}}

\begin{document}

\bal
	\frac{3.5}{4.2} &= \frac{35}{42}\\
	&= \frac{5}{6}
\eal

\end{document}

I just didn't have a good answer to give to him.  Can some expert out there explain?

Thanks.

David