A22-ft by 28-ft rectangular swimming pool is surrounded by a walkway of uniform width. if the total area of the walkway is 336 ft2, how wide is the walkway?

I would just use trial and error, it's the easiest way to do it, so find out the area of the pool, then just add that to 336 to get the total area. then add a couple of feet to the dimensions of the pool until you get an answer that matches the total area ( I got 952 for the total area) once you find a number that you can add to 22 and 28 and when you multiply them to get 952 your answer should be the number you added to 22 and 28
I don't know if that helps at all, but thats the only way I can explain it.
the answer I got was 6ft

It is going to be the third choice