Spaceship A moves away from Earth at a speed v_A = 0.728c (see figure). Spaceship B pursues at a speed v_B = 0.837c relative to Earth. Observers on Earth see B overtaking A at a relative speed of 0.109c. With what speed is B overtaking Aas seen by the crew of spaceship B?

S S' VA VB X Spaceship B Spaceship A