How do I solve this?

In an electronpositron collider, the electron is accelerated to an energy of 5.11 MeV. The electron mass is 511 keV/e2. (a) What is the velocity (expressed as 11/ c), kinetic energy, and momentum of the electron? A positron is accelerated in the opposite direction to the same energy and collides with the electron. (b) What is the maximum Imiss of a new particle X created by the collision [6\" +(:_ > X] ? What is the new particle's momentum in this case? (e) What is the velocity ((ucpressed as We) of the positron in the electron's rest frame? [Carefull This calculation requires some precision] (d) What is the total energy in this frame? Discuss why most accelerators new use colliding beams as opposed to xed targets. A new particle, the Teehion, is created with a rest mass 3 MeV and total energy' 6 MeV in the laboratory frame. In the lab frame, the Teehien travels 2 In between where it is created and where it decays. (e) What is the proper dway time {i.e., the decay time in its own rest frame} for the Ttslion