For me, a 27 year old, it comes down to this. Do you want to be a raging child, or do you want to step up and be a leader?
I've gone 11-0. Then sometimes, I'll go 0-11. Sometimes people will have bad games. Mine usually come when my lane mate is a runner not a fighter, so when this happens, I make sure I play a little more D minded. I would love nothing more than to run in there and kill them. But with my champ selections, it can't usually be done alone. I don't yell at them, I communicate. If I want to go for it, I communicate to them and set up a stategy. If they don't confirm they understand, guess what? I hug my tower if need be. As someone said above, you adjust to your mates playstyle.
Also, if someone is so terrible, then they can't have a good ELO. If they don't have a good ELO, then why did they get matched in a game with you? Oh, because you don't have a good ELO either.
Just blew your mind right there didn't I?