After 4 years, the ratio of age of A and B is 7: 6. The present age of C is thrice the present age of D. The age of C is 6 years younger than the age of A. If the age of D after 11 years is 17 years, then find the age of B 5 years ago.
1
16 years
2
20 years
3
15 years
4
12 years
5
18 years