Math & Science ⇒ linear equation with curved bracket and numbering

[dejhost]

Hi.
I am rather new to latex. Would you please help me to align the following linear equation, so identical terms stand straight below each other? Also, I'd like to have a curved bracket (left side) and finally, I'd like to know how to display one, common number for both lines (e.g.: "1"), but I'd also like to learn how to display each line having its own subnumbering (e.g. "1.0" and "1.1"). I tried all kind of classes (equation, systeme etc.) but do not manage to get all the things I am looking for into place.

Code: Select all

\documentclass{article}
\usepackage{amsmath}
\begin{document}

\begin{subequations}
	\renewcommand{\theequation}{\theparentequation.\arabic{equation}} 
	\begin{alignat}{4}
		&-X_{i}^{T} A & + x_{i}X_{i}^{T}C    = 0  \\
		&-X_{i}^{T} B & + y_{i}X_{i}^{T}C    = 0  
	 \end{alignat}
	\label{eqn:all-lines}
\end{subequations}

\end{document}

Your help is much appreciated.