A muon with rest energy 106 MeV is created at an altitude of 4500 m and travels

Question:

A muon with rest energy 106 MeV is created at an altitude of 4500 m and travels downward toward Earth's surface. An observer on Earth measures its speed as 0.980c.
(a) What is the muon's total energy in the Earth observer's frame of reference?
(b) What is the muon's total energy in the muon's frame of reference?