Hello! To find out how many inched the hallway is, you first need to know how many inches are in a yard. You need to find the operation that will be needed for this problem, and I'm assuming you don't know, what you want to do is ask yourself,"What am I trying to find? Wold this best be accomplished with subtraction or division, or multiplication or addition? Am I looking for what the difference between two, or how many items are needed for even groups? Do I want to find out how long something will be when added to something else, or multiplied?
I hoped this helped! If you have any further questions pertaining to this problem, feel free to shoot me a message or another question! Good luck :)