The average of 12 numbers is 48. The average of the first 5 numbers is 45 and the average of next 4 numbers is 52. If the 10th number is 10 less than the 11 th number and is 5 more than the 12th number, then the average of the 11 th and 12th numbers is:
A.
50.5
B.
46.5
C.
47.5
D.
48.5
Solution:
-