%% 
%%  Example 01-06-4 
%%  Copyright (C) 2017 Herbert Voss
%% 
%% ==== 
% Show page(s) 1
%% 
%% 
\documentclass[]{screxa}
\pagestyle{empty}
\setlength\textwidth{328.62788pt}

%StartShownPreambleCommands
\usepackage{mathtools}% for \boxed 
%StopShownPreambleCommands
\begin{document}
\begin{subequations}
\begin{minipage}{0.45\textwidth}
\begin{equation}
\fboxsep=0pt\fboxrule=0.1pt
\boxed{\sum_{%
  \makebox[0pt]{$
    {{\scriptscriptstyle 1\le j\le p\atop {{1\le j\le q\atop 1\le k\le r}}}}%
  $}}%
}\boxed{a_{ij}b_{jk}c_{ki}}
\end{equation}
\end{minipage}\hfill
\begin{minipage}{0.45\textwidth}
\begin{equation}\label{eq:disp-limits3}
\sum_{%
  \makebox[0pt]{${{\scriptscriptstyle 1\le j\le p\atop {%
     {1\le j\le q\atop 1\le k\le r}}}} $}}a_{ij}b_{jk}c_{ki}
\end{equation}
\end{minipage}
\end{subequations}
\end{document}
