Answer:
42
Explanation:
Each ages at the same rate. In 3 years, all will be 3 years older.
Application
The sum of their ages now is ...
A +J +D = 33
In 3 years, the sum will be ...
(A +3) +(J +3) +(D +3) = (A +J +D) +(3 +3 +3) = 33 +9 = 42
In 3 years, the sum of their ages will be 42.