Need help with this word equation, tks

I need help in trying to solve this word problem equation. The answer is 344 M, but have no clue how to set it up.

A walkway 3m wide is constructed along the outside edge of a square courtyard. If the perimeter of the courtyard is 320m, what is the perimeter of the square formed by the outer edge of the walkway.

Ok now when it says constructed along the outside edge of the square courtyard, IT MEANS all the way around????

So it's asking for the total new size correct???

HELP PLEASE and thanks

Jo