Question
John, Luis and Billy have some pens. The ratios of their pens are as follows:

John : (John + Luis + Billy) = 3 : 7
Luis : (John + Billy) = 1 : 3

Billy has 12 pens more than Luis. In the end, Billy gives away all he has to Luis and John so that both Luis and John end up with the same number of pens, how many pens has John received from Billy?
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John, Luis and Billy have some pens. The ratios of their pens are as follows:

John : (John + Luis + Billy) = 3 : 7
Luis : (John + Billy) = 1 : 3

Billy has 12 pens more than Luis. In the end, Billy gives away all he has to Luis and John so that both Luis and John end up with the same number of pens, how many pens has John received from Billy?