Afking vs Losing in Ranked

I just realized that someone loses an average of about 20 Lp per game. If you afk, i dont think you lose 20 Lp. Maybe like 10 which is better. If your team is down by 15 kills to none at 14 mins, than is it reasonable to afk as you might lose less lp? I really dont carry about afk time and small elo changes. Sorry for being noob, but I litterally could not find one article or website saying how much lp lost for an afk. How much do u lose afking vs losing without afking?