Are you sure you want to solve this using the Order of Operations? or you just want to find the value of r ?
6r + 11 = 39 eliminate 11 at the left side by subtracting it both sides
6r = 39 - 11 simplify the right side
6r / 6 = 28 / 6 divide both sides with 6 to remain the value of r
r = 4 2 / 3 or 4.666...