i tried to slove this assginment but i couldn't nothing is working out... please can someone solve a sample for me?

the assignment is to develop a spreadsheet that will manage invoices of clients in a wholesale company. Take the name of the client, the category (commercial, educational...), the number of the invoice in question, the date of the invoice, the due date of the payment, and the real date of the payment. let the clients get different discounts according to their category and the payment before the due dates. put this in an "if" and drag it to every client (around 50).