I bet you don't know this one

[StuW]

3 points in space A - B - C. B has been moving away from A for 13.8by and C has been moving away from B for 13.8by so why can't the universe be 27.6by in size wyrd? (Its completely innacurate but demonstrates a basic point). Using the same idea, if A was moving away from B at 99.9%c and C was moving away from B at 99.9%c, how fast is A moving away from C? ...199.8%c because relative velocities are not constrained, just absolute velocities. Therefore relative to the space expanding at >c its still less than c in the absolute frame of reference. That's how i understand it anyway.