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Math Help - need help plz, counting

  1. #1
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    need help plz, counting

    In a kindergarten class of 32 childern,15 have brothers,14 have sisters and 8 have neither sisters nor brothers.how many childers in this class have both brothers and sisters
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by gracy View Post
    In a kindergarten class of 32 childern,15 have brothers,14 have sisters and 8 have neither sisters nor brothers.how many childers in this class have both brothers and sisters
    Let a have brothers only, b have sisters only and c have brothers and sisters.

    Then

    a+b+c=32-8=24 ..(eq1)

    also

    a+c=15 ..(eq2)

    and

    b+c=14 ..(eq3)

    Subtract eq2 from eq1 gives:

    (a+b+c)-(a+b)=24-15,

    so

    c=9,

    hence a=6, and b=5.

    RonL
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