We do not do your homework: it is set for a reason. It is there so that you think about what you have been told, and try to understand it. It is also there so that your tutor can identify areas where you are weak, and focus more attention on remedial action.
Try it yourself, you may find it is not as difficult as you think!
But here are the basic principles:
http://www.purplemath.com/modules/mtrxadd.htm[
^] in case you have forgotten how to do it...