If from each of the three boxes containing 3 white and 1 black, 2 white and 2 black, 1 white and 3 black balls, one ball is drawn at random, then the probability that 2 white and 1 black ball will be drawn is given by \( \frac{a}{b} \) where \( a \) and \( b \) are relatively prime. then \( a + b \) is given by

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