What are the steps of getting from equation 1 to equation 2?

This problem is from a solution key to a practice test:

I am struggling to see how the teacher got from equation 1 to equation 2. I've tried using this quality factor equation:

And I know that the N=16 comes from the fact that the PLL multiplies the input frequency by 16. But I am still not able to get to equation 2. What are the steps to get from equation 1 to equation 2?