Answer:
We conclude that have 96390 different schedules.
Step-by-step explanation:
We know that In choosing what music to play at a charity fund raising event, Cory needs to have an equal number of piano sonatas from Mozart, Brahms, and Schubert. If he is setting up a schedule of the 6 piano sonatas to be played, and he has 18 Mozart, 3 Brahms, and 21 Schubert piano sonatas.
We calculate how many different schedules are possible:

We conclude that have 96390 different schedules.