9
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Given that 10 is the arithmetic mean of the set $\{6, 13, 18, 4, x\}$, what is the value of $x$?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
9
Given that 10 is the arithmetic mean of the set $\{6, 13, 18, 4, x\}$, what is the value of $x$?
train