Physics Question, Ive tried so many times PLEASE HELP

Question

No matter what I try, I cannot get this question right,

Use the Bohr model to estimate the energy (in eV) of the K_β line in the X-ray spectrum of platinum (Z=78). (h=6.626×10^-34 J.s, c=3×10⁸ m/s, 1eV = 1.6×10^-19 J)

Use the Bohr model to find the energy difference to produce the X-rays.

Answer 1

I'm no expert in atomic physics or anything, but seems to be an application of Moseley's Law. Z = 78 for platinum. The 8/9 is determined by the K-beta line, which is a transition from the 3rd shell down to the first shell. I would still double check my numbers.