1. The problem statement, all variables and given/known data A positron with kinetic energy 2.2MeV collides with an electron at rest, and annihilate each other. a. Calculate the average energy of the two gamma photons produced as a result of annihilation 2. Relevant equations 3. The attempt at a solution I would infact calculate the energy in the left hand side including the rest masses.. isn't it.. So it would be (0.511 x 2) + 2.2 = 3.222 MeV .. But this doesn't seem the answer.. Any help guys???