Hydrogen Atom - Electron Transitions

Q.
calculate the wavelength of light emitted when each of the following transitions occur in the hydrogen atom. n=5---n=3
A.
The energy of a hydrogen electron at the nth energy level is:
En = -B/n^2
where B = 2.179x10^-18 J, a constant
The energy of the transition is:
E = E5 - E3
or
E = [(-2.179x10^-18 J) / 5^2] - [(-2.179x10^-18 J) / 3^2] = ______ ?

After you find the transition energy, E, you calculate the frequency, f, using, E = hf, or
E = (6.626x10^-34 Js)(f)
or
f = E / (6.626x10^-34 Js)

Finally,
Use
(wavelength)(frequency) = (3.00x10^8m/s)
or
wavelength = (3.00x10^8m/s) / freq. = ______?

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