Here is the problem :

-Billed DLSU professors 15,000 for the processing of their travel papers.
And the other is
-Arranged a pilgrim trip for DLSU prof. Billed PAL 10,000 as a commission.

What is the entry in a general journal? And what is the credit and debit?

"Billed" means that they did not pay you at the time you did the work, so you sent them a bill for the amount that is due. It means Accounts Receivable, which is a debit account.