[Question] What do I do when greeting someone and they put their wrist up sideways

sometimes when i run into someone i know in the halls in school they'll either put their hand out to kinda like slap shake ny style or something and then othersll fist bump or something

but sometimes someone would put their arm up in a diagonal way kinda like a diagonal line across their chest with their hand making a fist kinda like they're holding a mic to their mouth but further away from their chest.

what ive gathered is that youre supposed to do the same thing and hit your forearms / wrists together but idk if im doing it wrong and it ends up with some awkwardness from me. i live in ny if it helps, since it could be a ny thing but im so confused

i realize this is such a shit post but i really want to know