Row Reduction & Rank · Easy problem

$\begin{pmatrix} 1 & 2 & 0 \\ 0 & 1 & 4 \end{pmatrix}$

$\begin{pmatrix} 0 & 1 & 5 \\ 1 & 0 & 2 \end{pmatrix}$

$\begin{pmatrix} 1 & 0 & 3 \\ 0 & 1 & -2 \end{pmatrix}$

$\begin{pmatrix} 2 & 0 & 1 \\ 0 & 1 & 3 \end{pmatrix}$