How to increase the horizontal space in an array below?

\documentclass[preview,border=12pt,12pt]{standalone}
\usepackage{mathtools}

\newcommand\specifier{%
r@{}r@{}l
r@{}r@{}l
@{}c}

\newcommand\operator[1]{~\smash{\raisebox{.8\normalbaselineskip}{$#1$}}}

\begin{document}
$\begin{array}{\specifier} 3x & {}+ 2y & {}=7 & \action{1} & 3x & {}+ 3y & {}= 7 \\[\jot] x & & {}=22 & \action{3} & 3x & & {}= 66 & \operator{+} \\\cline{5-7} %& & & & \multicolumn{3}{l}{\rule{25mm}{1pt}} &$+$\\ & & & & & 3y & {}= -59 \\[\jot] & & & & & y & {}= - 59/3 \\ \end{array}$
\end{document}


I want to increase the space of

such that it becomes as follows. The red line shows the space I mean.

How to increase the horizontal space in an array?

• Up to now I still don't understand why we have to write mathematical expression with array as shown above where each term must be separated to get proper alignment. It makes the writing look unnatural. A smart package should be developed. – kiss my armpit May 19 '14 at 5:19
• Well, I thought I gave you more natural syntax at tex.stackexchange.com/questions/177501/… :^), but you chose to go with the array approach 8^b – Steven B. Segletes May 19 '14 at 10:43

Instead of using \cline, you could use \cmidrule of the booktabs package. The added bit of vertical spacing provided by \cmidrule may just suit your needs.

\documentclass[preview,border=12pt,12pt]{standalone}
\usepackage{mathtools,booktabs}

\newcommand\specifier{%
r@{}r@{}l
r@{}r@{}l
@{}c}
\newcommand\operator[1]{~\smash{\raisebox{.8\normalbaselineskip}{$#1$}}}

\begin{document}
$\begin{array}{\specifier} 3x & {}+ 2y & {}=\phantom{0}7 & \action{1} & 3x & {}+ 3y & {}= \phantom{-0}7 \\[\jot] x & & {}=22 & \action{3} & 3x & & {}= \phantom{-}66 & \operator{-} \\ \cmidrule{5-7} %& & & & \multicolumn{3}{l}{\rule{25mm}{1pt}} &$+$\\ & & & & & 3y & {}= -59 \\[\jot] & & & & & y & {}= - 59/3 \\ \end{array}$
\end{document}

\documentclass[preview,border=12pt,12pt]{standalone}
\usepackage{mathtools}

\newcommand\specifier{%
r@{}r@{}l
\newcommand\operator[1]{~\smash{\raisebox{.8\normalbaselineskip}{$#1$}}}
$\begin{array}{\specifier} 3x & {}+ 2y & {}=7 & \action{1} & 3x & {}+ 3y & {}= 7 \\[\jot] x & & {}=22 & \action{3} & 3x & & {}= 66 & \operator{+} \\\cline{5-7} %& & & & \multicolumn{3}{l}{\rule{25mm}{1pt}} &$+$\\ \xstrut & & & & & 3y & {}= -59 \\[\jot] & & & & & y & {}= - 59/3 \\ \end{array}$