How do i handle ranked games?!

Fifth time i was in promo to platinum, lost of course... What am i supposed to do, how do i handle flamers/feeders/trollers? Most of the time I am the one who is doing best on our team but it's impossible to carry an entire team since this is a teambased game, do you have any tips? and dont say "Dont take all the kills" because i try to get my teamates fed as well but they sort of dont do any progress or contribute anything... Also "focus on your own gameplay and complain about others" since i try to give advise to the people on my team.
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