For the situation of, what multiple of h2/8mL2 gives the energy of (a) The first excited state,

Question:

For the situation of, what multiple of h2/8mL2 gives the energy of
(a) The first excited state,
(b) The second excited state,
(c) The third excited state of the system of eight electrons?
(d) Construct an energy-level diagram for the lowest four energy levels of the system.