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2007 AMC 10B Question 25

AMC10 · 2007 AMC 10B

Question 25

How many pairs of positive integers $(a,b)$ are there such that $a$ and $b$ have no common factors greater than $1$ and

$$
\frac{a}{b}+\frac{14b}{9a}
$$

is an integer?
  1. $4$
  2. $6$
  3. $9$
  4. $12$
  5. infinitely many