Two protons are moving away from each other. In the frame of each proton, the other proton has a speed of .555c.[In the rest frame of the earth the protons are moving in the opposite directions with equal values of speed. What does an observer in the rest frame of the earth measure for the speed of each proton? Enter your answers numerically separated by a comma I thought I would just divide by 2.... clearly it is wrong. The answer is .303c, after failing many tries on mastering physics. I want to know how you do this problem. Thank you.