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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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Hints/Tips re: I agree ======i do not agree with you | Comment 3 of 5 |
(In reply to I agree by broll)

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

15b+20g=305,    WRONG   305 should include parents' part too

hint: 

     let g denote the number of girls , b - boys, c=b+g   number of chldren and p=c/3  parents

SOLVE IN INTEGERS

  17g+12(c-g)+9c/3=305 

which reduces  to  5g+15c=305

 i.e. g+3c=61     where c>g     and   3 divides c

\.............g=7  c=18         p=6.................../

why not edit your post??


  Posted by Ady TZIDON on 2018-02-13 06:49:22
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