Answer
Two matrices are added by adding the corresponding elements and only if they are of the same order.
Work Step by Step
Two matrices can be added by adding the corresponding elements only if they have the same numbers of rows and columns (the orders must match)
If they are of different orders, there would be a minimum of one extra row or column in one of the matrices.
Example:
Consider two matrices of order $2\times 2$: $A=\left( \begin{matrix}
a & b \\
c & d \\
\end{matrix} \right)$ and $B=\left( \begin{matrix}
e & f \\
g & h \\
\end{matrix} \right)$
Then, the addition operation on the matrices is performed as follows:
$\begin{align}
& A+B=\left( \begin{matrix}
a & b \\
c & d \\
\end{matrix} \right)+\left( \begin{matrix}
e & f \\
g & h \\
\end{matrix} \right) \\
& =\left( \begin{matrix}
a+e & b+f \\
c+g & d+h \\
\end{matrix} \right)
\end{align}$
