Answer:
$3
Explanation:
The money shared by Ben and Carol was split ...
... Ben : Carol = 1 : 3
The difference of these ratio numbers is 2, and the difference in amount received is $6. Thus, each ratio unit must stand for $6/2 = $3.
... Ben received 1×$3 = $3
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The Rest of the Story
Carol received 3×$3 = $9. Together, Ben and Carol received $3 + 9 = $12, which is 4/5 of the total amount. Then the 1/5 of the total amount that Alice received is
... (1/5)×$12/(4/5) = (1/4)×$12 = $3.
The $15 of money was split ...
... Alice : Ben : Carol = $3 : $3 : $9