For adding matrices, their dimension should be equal.

First write the dimension of the matrix.

The first matrix is,         

The matrix has 3 rows and 3 columns, so dimensions of matrix are .

The second matrix is,

The matrix has 3 rows and 3 columns, so dimensions of matrix are .

The dimensions of matrix are equal. The operation of addition is possible.

Add the corresponding elements.

                                               (Simplify)

The solution is