The average of eleven numbers is 54. The average of the first four numbers is 48 and that of the next four numbers is 25% more than the average of the first four. The ninth number is 8 greater than the $$11^{th}$$ number and the tenth number is 4 greater than the $$11^{th}$$ number. What is the average  of the $$9^{th}$$ and the $$10^{th}$$ numbers?

A

52.6

B

54

C

56

D

54.4