@Shockdrop, here's how we were getting "R"
m and n would be the 2 middle letters.
m = 13, +2 = o (15th letter), -7+-3=-10 = e (5th letter), +-2 = c (3rd letter), x3 = i (9th letter), x3 = 27/2 = 13.5 = not associated with any # of the alphabet
n = 14, +2 = p (16th letter), -7+-3=-10 = f (6th letter), +-2 = d (4th letter), x3 = L (12th letter), x3 = 36/2 = 18 = R
Yes, 13 would be the true middle number, but you said there were 2 possible answers, one was right, one was wrong, so i figured the one that actually led to a letter was the right one. But I see what you were getting at with the 13.5 answer.