demoted

so, i won like 7/10 ranked games and it placed me bronze 5, my friend at school won like 3-4 outta 10 and got bronze 2, and made fun of me saying he was better than me, I'm bronze 4 atm, so when he left discord, cause he went to do ranked, so i prayed he loses his ranked games and get demoted to bronze 3, i thought it was 3 losses at 0lp that gets demoted, so he lost 3 games but still bronze 2, can anyone tell me if its random? or maybe 4-5 losses?