<P>hey

here is your answer

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let the number of white marbles = w  

let the # of blue marbles = b  

let the # of GREEN marbles = g  

=> b + w + g = 54  

Probability of an event = # of ways an event can occur / total # of OUTCOMES  P(b) = 1/3  

[ Number of ways it can happen: b (there are b blues)  

Total number of outcomes: (b + w + g) (there are 54 marbles in total) ]  

=> b / (b + w + g) = 1/3 ---------------------> (i)  

P(g) = 4/9  

=> g / (b + w + g) = 4/9 ------------------------> (II)  

(i) + (ii) => (b + g) / (b + w + g) = 1/3 + 4/9 = (3 + 4)/9 = 7/9  

=> 9(b + g) = 7(b + w + g) = 7 x 54  

=> b + g = 42 marbles (blue and green)  

or white marbles w = 54 - 42 = 12  

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hope this helps

thanx and be brainly................................................................