Tabular and equation in a text line

Question

I want to do something like this:

in a line with text, not center. Also I can control the left brace but it doesn't seems good.

My MWE is:

\documentclass{article}
\usepackage{amsmath,cancel}
\newcommand\MyLBrace[2]{%
\left\{\rule{0pt}{#1}\right.\text{#2}}\newcommand\numberthis{\addtocounter{equation}{1}\tag{\theequation}}
\begin{document}
   Add m.t.m $\MyLBrace{5ex}{
   \begin{tabular}{r}
   21x\;-\;\cancel{6y}=24\\ 
   4x\;+\;\cancel{6y}=26 \\ \hline
   25x=50\\x=2\;\, 
  \end{tabular} }$
\end{document}

which result in this:

Any help, please?

Answer 1

This is close.

\documentclass{article}
\usepackage{mathtools,cancel}
\begin{document}
   Add m.t.m $\
   \begin{cases}
   \begin{aligned}
   21x - \cancel{6y} &= 24\\
   4x + \cancel{6y}& =26 \\[\jot] \hline
   25x &=50\\
   x &=2
   \end{aligned}
   \end{cases}
  $
\end{document}

With lot of arrays, you can do this:

\documentclass{article}
\usepackage{amsmath,cancel,array}
\begin{document}
   $\begin{array}{@{}r@{\,\,}r@{}}
   \text{Add m.t.m} & \left\{
   \begin{array}{r@{}}
   21x - \cancel{6y}=24\\
   4x + \cancel{6y}=26 \\ \hline
   25x=50
  \end{array}\right.\kern-\nulldelimiterspace\\
  & x=2\phantom{0}
  \end{array}$
\end{document}

Answer 2

For the sake of variety, here's a solution that uses one tabular and two array environments. The second array environment is set up to get the spacing around symbols of type mathbin and mathrel right.

\documentclass{article}
\usepackage{array,cancel}

\begin{document}
\[
\begin{tabular}{c}
 \\ text here text here \\ \\ \\
\end{tabular}
\begin{array}{@{}c@{}}
   \left\{ \begin{array}{@{}c@{}} \\ \\ \\ \end{array} \right. \\ \\ \end{array}\,
\begin{array}{@{} r @{}>{{}}c<{{}}@{} r @{{}={}} r @{}}
   21x & - & \cancel{6y} & 24\\
    4x & + & \cancel{6y} & 26\\
   \hline
   & & 25x & 50\\
   & &   x  & 2\\
\end{array}
\]
\end{document}