Consider the sequence of six real numbers: 60, 10, 100, 150, 30, and $x$. The average (arithmetic mean) of this sequence is equal to the median of the sequence. What is the sum of all the possible values of $x$? 

Note: The median of a sequence of six real numbers is the average of the two middle numbers after all the numbers have been arranged in increasing order.

Let's think step by step and output the final answer within \boxed{}.
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