Just need the working out and answer for this question. Thank you.

A medicine school student is deciding whether to become a general practitioner or specialize in immunology. The expected income he would get per period from these choices is presented in the table below. Period 1 Period 2 Period 3 General practitioner 20 200 180 lmmunologist 100 250 220 a. What is the internal rate of return of becoming an immunologist versus a general practitioner? b. What will the student choose if his discount factor is 0.95