Step-by-step explanation:
The important rule to know is that when adding and subtracting matrices, first make sure the matrices have the same dimensions. In order words, you can add or subtract a 2x3 with a 2x3 or a 3x3 with a 3x3. However, you cannot add a 3x2 with a 2x3 or a 2x2 with a 3x3.
