Guys: When you're talking about things happening near the speed of light, you need to work in a special relativity framework. This is not a trick question, and the answer is neither 1.2c (c is the speed of light) nor 0.6c (he's asking that if a person on P sees A moving away at 0.6c and B moving the other way at 0.6c, how fast does B appear to be moving away to someone who is standing on the surface of A).
The real answer is that you need to calculate things differently due to special relativity. The formula for that is to express vA and vB in units of c, then divide the sum of the velocities by 1 plus the product of the velocities. For this problem, that comes out to about 0.88c, so someone on A sees B moving away at 88% of the speed of light. How does that work? Time dilation.
tl;dr The universe is fuckin' crazy yo.