A pion is decaying into a muon and a neutrino:
π⁺ → μ⁺ + vμ
Assuming the pion is at rest, use energy and momentum conservation to calculate the energies E and E, (calculate numerical values in MeV) of the muon and neutrino after the decay, as well as the Lorentz factory and normalized velocity B of the muon. You may treat the neutrino as massless, i.e., it behaves as if it was a photon.