We can solve this problem by setting up an equation. Let's say that x is the total time it takes to do the interview. So far, Agent Y has completed 4/9 of the interview or 4/9x. Since 4/9 of the interview was finished in 2 hours:
4/9x = 2
We can multiply by the reciprocal of 4/9 to get x.
x = 2 * 9/4
x = 4.5
This means that it took Agent Y 4.5 hours to finish the interview.