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Math Help - SAT Question

  1. #1
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    SAT Question

    If n and p are integers greater than 1 and if p is a factor of both n+3 and n+10, what is the value of p?

    (a)3
    (b)7
    (c)10


    (d) 13

    (e)30

    the answer is b but i don't know why
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  2. #2
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    Quote Originally Posted by juliak View Post
    If n and p are integers greater than 1 and if p is a factor of both n+3 and n+10, what is the value of p?

    (a)3
    (b)7
    (c)10


    (d) 13

    (e)30

    the answer is b but i don't know why

    An easy-to-prove little lemma: if p divides a and p divides b then p divides a - b

    Tonio
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