John computes the sum of the elements of each of the 15 two-element subsets of $\{1,2,3,4,5,6\}$. What is the sum of these 15 sums?
Question:
John computes the sum of the elements of each of the 15 two-element subsets of $\{1,2,3,4,5,6\}$. What is the sum of these 15 sums?
Answer:
Let's think step by step.

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John computes the sum of the elements of each of the 15 two-element subsets of $\{1,2,3,4,5,6\}$. What is the sum of these 15 sums?
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