Debit: bank deposit 100
Loan: main business income 100.
Joint transportation expenditure
Debit: main business cost 70
Loan: bank deposit 70
Tax = (100-70) * 3% = 0.9
Borrow: the main business cost plus tax is 0.9.
Loan: tax payable-business tax payable 0.9
I hope I can help you!