Hydrogen Atom - Electron Transitions

Q.
A exited hyrogen atom emits light with a frequency of 1.141 x10^14hz to reach the energy level for which n=4 in what principal quantum level did the electron begin.
A.

A exited hyrogen atom emits light with a frequency of 1.141 x10^14hz to reach the energy level for which n=4 in what principal quantum level did the electron begin

The energy of the photon with a given frequency, f, is:
E = hf
For this example,
E = (6.626x10^-34 Js)(1.141 x10^14 hz) = _______?

Also,
E = E(higher) - E(lower)
or
E = Ex - E4 x is the higher level
or
E = E(higher) - (-2.179x10^-18 J / 4^2
or
E(higher) = (2.179x10^-18 J / 4^2) - E
Substitute E from the previous step and solve to get E(higher)

Finally,
E(higher) = (2.179x10^-18 J / x^2)
or
x^2 = 2.179x10^-18 J / [E(higher)] = ________?

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