Thanks. You got it off a room mode calculator I thought.
I'm not confident that I understand it correctly. That's why I was double checking with you. I attached a picture with my room measurements and indicated the 16' width column with a black arrow.
If I read it correctly I would place the first speaker 2' 3/4" away from the wall, and the second speaker 13' 1/4 away from the wall.
Subtracting 13.25 from 2.75 = 10.5 or 10'6" , which is two inches off from your suggested number. Am I doing it wrong? Or was your number off 2" ?