You must use ALGEBRA in order to solve this problem.
Step 1. T= Tray's age and J= Jan's age
Step 2. (T*2)-3 and T+J=30
Step 3. Tray must be 11 because and Jan must be 19, it never said that Tray is OLDER.
Step 4. Recheck----- (11*2)-3=19
Sorry, I don't explain too well, I am used to doing it in my head... Hope this helps!!! :D