The formula HPO4 + CH4N2O, how many atoms would be in the H? Or the P? Or the O that is at the end of the formula. I greatly appreciate your response.

This is only a guess, just to see how dumb I am am I guess.
But the first set (HPO4) which is hydrogen phosphate is one hyrogen. Represented by the H. The second set (CH4N20) which I believe is urea, which is a mammalian urine, has 4 hydrogen, represented by the H4. So total in this complete set there are 5 hydrogen atoms. There is one total phosphorus atom. 5 total oxygen atoms. 1 Nitrogen atom, and 1 carbon atom.

I believe mixing these two chemicals comes out with a chemical close to urea phosphate. Which is a fertilizer. :D.
I am probably wrong but it's been 7 years since biology and chemistry LOL

Rick