hotel fare = subtotal - cleaning
hotel fare = 578 - 60
hotel fare = 518
hotel nightly rate = 518 / 2
hotel nightly rate = 259
So, we can back out all of the numbers, but we can’t have the fields for these values be formulas sometimes, and numeric others. So, for all of the fields that you’re going to have empty sometimes, you need additional formula fields that calculate everything like I did above.
I hope that’s clear and mistake free (and that I understood your problem correctly). Good luck!