Naturally we remember that we just add them entry by entry to find the answer:

2 + 0 = 2; 10 + 2 = 12; 8 + 0 = 8; 4 + 1 = 5

and

Example 3

Use these matrices for the example:

2(A + C)

Here we have one number that will be multiplied through two matrices thanks to the distributive property you remember from your Way Back Machine, so this:

2(A + C)

ends up being this:

2A + 2C

and as we already know, we just substitute our matrices for the variables and get:

Next we multiply the 2.

At which point we recognize that this is a simple addition of matrices situation and that the entries that correspond with each other in the two matrices get added together: