Adding and Subtracting Matrices

$A - B = B - A$

If $C - A = B$ and $B - A = C$, then every entry of $A$ is zero.

$C - (A - B) = B - (A - C)$

$A - A = B - B$

$\begin{pmatrix} 2&4\\6&1 \end{pmatrix} - \begin{pmatrix} -1&2 \end{pmatrix}= \begin{pmatrix} 3&2\\6&1 \end{pmatrix}$