%% 
%%  Der Mathematiksatz mit LaTeX, 1. Auflage 2009
%% 
%%  Example 9-12-1 on page 187.
%% 
%%  Copyright (C) 2009 Herbert Voss
%% 
%%  It may be distributed and/or modified under the conditions
%%  of the LaTeX Project Public License, either version 1.3
%%  of this license or (at your option) any later version.
%% 
%%  See http://www.latex-project.org/lppl.txt for details.
%% 

\documentclass[]{ttctminimal}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{355.65944pt}
\AtBeginDocument{\setlength\parindent{0pt}}
\setcounter{equation}{5}
\renewcommand\theequation{9.\arabic{equation}}
\StartShownPreambleCommands
\usepackage{amsmath,empheq,xcolor,graphicx}
\newcommand*\mycolbox[1]{%
  \colorbox{blue!30!yellow!40}{\hspace{1em}#1\hspace{1em}}}
\StopShownPreambleCommands
\begin{document}
\begin{subequations}
\begin{empheq}[% Beginn der Optionen
    box=\mycolbox,
    right={\;\makebox[.9em]{$\raisebox{-.5\totalheight+\fontdimen22\textfont2}
              {\resizebox{!}{\EmphEqdisplayheight+\EmphEqdisplaydepth}{!}}$}},
    left={X=Y\Rightarrow\empheqlbrace}]{alignat=3}
%
    A_1&=b_1 & \qquad c_1&=d_1 & \qquad e_1&= f_1
         \tag*{\_A\raisebox{1ex}{silly}\raisebox{-1ex}{tag}\_}\\
    A_2&=b_2 & \qquad c_2&=d_2 & \qquad  e_2&= f_2 \\
    A_3&=b_3 & \qquad c_3&=d_3 & \qquad  e_3&= f_3
\end{empheq}
\end{subequations}
\end{document}