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Pick-a-book meeting (Posted on 2018-02-12) Difficulty: 2 of 5
At a meeting of the Young Historical Society (YHS) in a local library the number of children present was three times the number of parents.
At this meeting, each boy borrowed 12 books from the library, each girl borrowed 17 books and each parent borrowed 9 books.
In total 305 books were borrowed.

How many girls were there at the YHS meeting?

See The Solution Submitted by Ady TZIDON    
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I agree | Comment 2 of 5 |

15 books per boy(b), 20 books per girl(g).

15b+20g=305, so 3b+4g=61. But also b+g=3 parents (p)

Substituting: 9p+g=61, and p=6, g=7, because if, say, p=5, then g= 16, and 16*20= 320, more than the given number of books.

So there were 7 girls at the YHS meeting.

What if the the number of children present was four times the number of parents?


  Posted by broll on 2018-02-12 22:04:32
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