(A2-8)  The thing with special relativity is that you have to be very careful about frames of reference. So when Cormorant says that the seabirds are each going to fly at 0.6c, he means relative to a “static” observer – which might be Nefertiti, if she can spare the time. So, in her frame of reference, the velocities will be wN for Cormorant and -wN for Shag.

Now, with the aid of the velocity transformation, work out the velocities of each bird in Cormorant’s frame of reference, and hence their combined velocities.