Respuesta :

48 min 

Mary is so clever :D 
Technically this has already been answered...

But here is what I got:

8:45 to 9:00 is 15 minutes

9:00 to 9:30 is 30 minutes

15+ 30 is 45 minutes.

Then add the 3 extra minutes to get 9:33 and your answer is 48 minutes.

So same answer.

How math works in my head^^^