% arara: indent: { overwrite: on, trace: yes}
\begin{tabular}{p{3cm}|c|p{8cm}}
Example & Choice & Why \\ \hline \hline
\(
\left\{
\begin{array}{rl}
x+y & =6 \\
2x+y & =8
\end{array}
\right.
\)
& Substitution {\em or }Addition & Because it is easy to solve for $x$ in the 1st equation
{\em or}
Because it is easy to multiply the first equation by -1 \\ \hline
\(
\left\{
\begin{array}{rl}
3x-7y & =13 \\
6x+5y & =7
\end{array}
\right.
\)
& Addition & Because there is no obvious way to use substitution \\ \hline
\(
\left\{
\begin{array}{rl}
x-7y & =13 \\
6x+5y & =7
\end{array}
\right.
\)
& Substitution & Because the first equation can easily be solved for one of the variables
\end{tabular}