From the condition, we can determine how many marbles of each color were there in the jar.


Indeed, we have these equations, where R is the number of red marbles, G is the number of green marbles and B is the number of blue marbles


    G + B = 6           (1)             ("all but 6 are red marbles")

    R + B = 8           (2)             ("all but 8 are green marbles")

    R + G = 4           (3)             ("all but 4 are blue marbles")


    ------------------------  Add equations (1), (2) and (3)


  2*(R + G + B) = 6 + 8 + 4 = 18   ===========>


     R + G + B = 9.     (4)


Now, subtracting from equation (4) equations (1), (2) and (3), one after one separately, we get


    R = 3;  G = 1;  B = 5.


Now the answer to the problem's question is  


    The ratio is   = ;


    The percentage is   = 44.44%.      ANSWER