Not a dumb question, just lots of unknowns....
What does your soil have to start with, is it rich or poor, do you need to just eep up or be building the soil?
What kind of yields can you hope for, is it winter or spring wheat, etc.
Wheat uses 1.2 lbs of N per bu
.52 lbs of P
.26 of K
So if you harvest 30 bu wheat, you'll want to add 15 lbs of P and 7-8 lbs of K just to keep your soil up. Now if you hope to yield more, or your soil is poor in these, them you'll want more....