Answer
[12 .... 16]
[14 .... 18]
Work Step by Step
You have two matrices:
[4 ... 6]
[5 ... 7]
[8 ... 10]
[9 ... 11]
Add the corresponding part of the 2 matrices:
[4+8 ... 6+10]
[5+9 ... 7+11]
New matrices:
[12 .... 16]
[14 .... 18]