You have the following matrices A and B:
In order to verify the commutative property A + B = B + A, remind that when you add two matrices, the elements of the new matriz are the result of the sum element by element of both matrices. For example, for the case of A+B, you have:
and for the case of B+A:
As you can notice, the result for the two cases is the same. With this the commutative property of addition is verified.