Debit: main business cost
Loans: Goods in stock
The question you asked is very good, because you are thinking about how the profits come out. At the end of the period, the income and the amount of the undergraduate course will be transferred to this year's profit, so that the ending balance of this year's profit will be profit. The entries are as follows:
Debit: main business income
Loan: profit this year
Debit: this year's profit
Loan: main business cost