Answer
Matrices (of the same order) are added by adding corresponding elements.
Work Step by Step
A matrix is a set of numbers, arranged into rows and columns, placed in brackets.
The numbers inside the brackets are called elements of the matrix.
A matrix of order $m\times n$ has $m$ rows and $n$ columns.
To add two matrices, they must have the same order. Otherwise, the sum is not defined.
Matrices of the same order are added or subtracted by adding or subtracting corresponding elements.
If we annotate $A=[a_{ij}]$ and $B=[b_{ij}]$, then
$A+B=\left[a_{ij}+b_{ij}\right]$