Calculate the frequency, in hertz, of the photon that is emitted when a electron falls from?

Question

Calculate the frequency, in hertz, of the photon that is emitted when a electron falls from level n = 9 to level n = 4 in the H atom.

Answer 1

I already did this exercise once. It's your turn now.

Answer 2

1/wavelength=1.09*10^7 ( 1 / n(1)^2- 1/n(2)^2)
n(1)=4 n(2)=9
frequency=c/wavelength c=3*10^8m/s