An astronomer on Earth measures the speed of light coming from the star Sirius, and measures u = c. Meanwhile, the astronomer also sees spaceship A racing by at 0.715c to the right. An observer in ship A sees a scientific research vessel, B, that is moving at 0.650c to the left, as measured from reference frame A. The scientists on research vessel B also measure the speed of light coming from the star Sirius. What speed do they measure? Express your answer as a multiple of c. Hint: you should not have to do any calculations.