# Marble Bag

A bag contains $$3$$ red marbles, $$4$$ blue marbles, $$6$$ yellow marbles, and $$6$$ green marbles. Four marbles are randomly drawn from the bag, without replacement. The probability of drawing a red, then blue, then green, and finally another red marble is $$\frac{a}{b}$$, where $$a$$ and $$b$$ are positive coprime integers. What is the value of $$a+b$$?

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