Tritium ({}_1^3 {\rm{{\rm H})}} is an unstable isotope of hydrogen; its mass, including one electron, is 3.016049 {\rm u}. Determine the total kinetic energy of beta decay products, taking care to account for the electron masses correctly. The answer is 1.86*10^-2 MeV, and I'd like to know how to do this. I tried several approaches, and none of them worked.