How do one code hunger drain rate based on sanity?

[Colden]

Hi, i am very new to coding, modding and like the title, i wonder how one can code hunger drain rate base on sanity

 

So my character have low max sanity(100), i want to make my character have their increased hunger drain while sanity drops base on how low it is(increased by 0.3 drain rate every 20 missing sanity, maxing out at x2.5 drain multiplier) to keep my character sanity perks fair for their upside perk

i have been trying to search info but i couldnt find anything related to problem, i am also not so good with english so some grammar maybe wrong, i hope anyone can help me with this, thank you <3