There are a certain number of red balls, green balls and blue balls in a bag. Of the balls in the bag, \frac13 are red and \frac27 are blue. The number of green balls in the bag is 8 less than twice the number of blue balls. The number of green balls in the bag is
Answer Choices
A. 12
B. 16
C. 20
D. 24
E. 28