In a colliding-beam apparatus, two beams of protons are aimed directly at each other. The first beam contains protons moving at a speed of 0.800c to the right, and the second beam’s protons have a speed of 0.900c to the left. Both speeds are measured relative to the laboratory frame. What are
(a) The velocity of the second beam’s protons relative to that of the first, and
(b) The velocity of the first beam’s protons relative to that of the second?