An electron (mass m) is contained in a rectangular corral of widths Lx = L and Ly

Question:

An electron (mass m) is contained in a rectangular corral of widths Lx = L and Ly = 2L.
(a) How many different frequencies of light could the electron emit or absorb if it makes a transition between a pair of the lowest five energy levels? What multiple of h2/8mL2 gives the
(b) Lowest,
(c) Second lowest,
(d) Third lowest,
(e) Highest,
(f) Second highest, and
(g) Third highest frequency?