The present age of A is 4 times more than the present age of B, whose age is 2/3 times of present age of C. D’s present age is 2 times more than the present age of C. If difference between the present age of A and C is 21 years, then find the ratio of age of A and D, 3 years from now.
1
9 : 8
2
8 : 9
3
10 : 11
4
12 : 13
5
11 : 10