In a round-robin tournament with $n$ teams, the number of games that must be played is $(n^2-n)/2$. How many teams are in a round-robin tournament in which 55 games are played?
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
In a round-robin tournament with $n$ teams, the number of games that must be played is $(n^2-n)/2$. How many teams are in a round-robin tournament in which 55 games are played?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
11
In a round-robin tournament with $n$ teams, the number of games that must be played is $(n^2-n)/2$. How many teams are in a round-robin tournament in which 55 games are played?
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