Tell those of us who don’t recognize it about Proscout. 30 seconds may not be long enough to show off both your acting and your singing voice. Get a timer and start reading lines to see how much time you actually have.
Older musicals like South Pacific or Guys and Dolls which incorporate songs into the dialogue, may be your best bet. Characters speak and then sing words which continue the subject which was being talked about.
Your age is also a factor when choosing a reading or song. It should probably be a character who is the age you look or can look.

Start with your monolgue and then break into an Ethyl Merman Medley

I was thinking somthing from Moulin Rouge.I don’t know :/