Nicky’s classroom is in the shape of a rectangle. his teacher wants to add a border around the walls. the length of the room is 22 feet and the width of the room is 15 feet. how long must the border be to go all the way around all four walls of the room?

So we have our length, 22, and our width, 15. We're trying to solve for the total length of all 4 walls of the room. This means we must add up all the sides.
Since the classroom is in the shape of a rectangle, our formula for the perimeter is 2L + 2W. 
Breakdown: 
2L + 2W = P
Plug in the length and width.
2(22) + 2(15) = P
Multiply 22 by 2, and 15 by 2.
44 + 30 = P
Add 44 and 30 to find the perimeter.
44 + 30 = 74
Your perimeter is 74 ft.
I hope this helps!