It seems like subtraction could be defined as adding a negation of a matrix.

If **A** and **B** have the same number of rows and columns, then
**A** - **B** is defined as **A** + **(-B)**.
Usually you think of this as:

To formA-B, from each element ofAsubtract the corresponding element ofB.

Here is a partly finished example:

Notice in particular the elements in the first row of the answer. The way the result was calculated for the elements in row 1 column 2 is sometimes confusion.