What is the cost invoice of the main business of the education consulting company?

Refers to invoices and bills that are directly or indirectly included in the operating cost and manufacturing cost of education. Article 73 of the Negotiable Instruments Law stipulates that a promissory note is a note issued by the drawer, which promises to unconditionally pay a certain amount to the payee or holder at sight. Promissory notes referred to in this Law refer to cashier's checks.