Outside dimentions

1.. The outside dimension of a living room are 13' x 22'. If the wall is 5 1/8" thick, what would the inside dimension of the room be?

2.. and also, how many square feet of flooring would I need for the answer to the first question?

[gubment_cheez]

12' 1 3/4" x 21' 1 31"
and 256 5/6ths ft²