(a) Determine the possible results of the measurement of the energy of this system and their relative probabilities. (b) What are the possible forms of the wave function immediately after such a measurement? (c) If the energy is immediately re-measured, what now will be the relative probabilities of the possible outcomes?

For this question I have the wavefunction at a paticular time and also the energy eigenvalues and eigenfunction. I understand the maths involved but I am struggling with working out what I have to do. I would be grateful of any help. Thanks