How should I deal with trolls?

I recently started playing ranked for the first time and landed in silver after a few messy games and I'm happy that I'm playing ranked now but i finally see how annoying trolls can really be and how childish and blind people can actually be while playing this game. My match just now was a great one (for the start of it anyway), I was jungle Sion and I had made a bunch of successful ganks even after being killed by rek sai at me red buff (which btw i got pay back for by doing the same to him as soon as I respawned) and we were even doing good considering we had an AP shaco support who liked roaming BUT things all went wrong when our ADC kept over extending knowing that the enemy support was a thresh and kept getting caught by thresh and ganks from rek sai which I tried my hardest to stop. After so long of bot lane our ADC appeared to be abit testy but I didn't take him for a guy who would troll or anything I just though he might be alittle steamed over what happened and I can't blame him but then after our bot tower fell. He roamed mid and was there for awhile and kept going back but our mid tower had fell and the enemy darius lost top so he roamed as well but our ADC kept pushing past our fallen mid tower without any teammates near him and kept dieing after being caught by reksai, thresh, and darius over and over again and each time blamed our akali who didn't want to help him because he knew that all he would do is die as well, then after about 3 death even though we were ahead in towers and kills he decided to AFk for about 30 seconds. After his cute little rage moment he then decided to assist the enemy team and feed the enemy on purpose by running under tower to let kat kill him as well as not attacking enemies to give them free kills.

The point of this long winded post that i used to vent my anger out from my game is what can I do to deal with assholes like this?

to clear things up Yes I know I'll see these guys are EVERYWHERE in ranked but there has to be something I can do to deal with them or atleast get them to actually think rationally and not blindly throw a bratty fit over small things so what is it?

Another thing is apparently he also did it because he knew tribunal was down or something so he though he wouldn't get in trouble for anything even if we reported him so another question is is the tribunal down and I don't know about it?