An astronomer on Earth evaluates the speed of light coming from the star Sirius and evaluates u = c. For the moment, the astronomer as well sees spaceship A racing by at 0.715c to the right. The observer in ship A sees a scientific research vessel, B that is moving at 0.650c to the left, as evaluated from reference frame A. The scientists on research vessel B as well measure the speed of light coming from the star Sirius. What speed do they evaluate? Illustrate your answer as a multiple of c.