well of course there is the energy of the emitted photon E = h f
but if they really want you to calculate the change in energy from one level to another that gets pretty complicated once you get beyond the Bohr model of the Hydrogen atom.
This might help:
https://en.wikipedia.org/wiki/Energy_level
When an electron move from one level to another an amount of energy is dissipated. Give the equation that will enable you to calculate that amount of energy
2 answers
I answered this question for you a day or so ago. Why are you asking it again?