plz help! ;(

 

A bag contains red, blue and green marbles. 2/3 of the marbles are not red and 3/4 of the marbles are not blue. What fraction of the marbles are not green? Express your fraction in lowest terms.     

 

Given that 2/3 of the marbles are not red, then 1/3 of the marbles are red.     

Given that 3/4 of the marbles are not blue, then 1/4 of the marbles are blue.     

 

1/3  =  4/12 are red         

1/4  =  3/12 are blue        

total    7/12 are either red or blue, so if they're red or blue they're not green     

_.