%% 
%%  Example 02-01-7 
%%  Copyright (C) 2016 Herbert Voss
%% 
%% ==== 
% Show page(s) 1
%% 
%% 
\documentclass[]{screxa}
\pagestyle{empty}
\setlength\textwidth{328.62788pt}
\setlength\parindent{0pt}
%StartShownPreambleCommands
\usepackage{amsmath}
%StopShownPreambleCommands
\begin{document}
\begin{alignat}{3}
   abc &= xxx             &&= xxxxxxxxxxxx &&= aaaaaaaaa \\
   ab  &= yyyyyyyyyyyyyyy &&= yyyy         &&= ab
\end{alignat}
\end{document}
