Here is the sample work I created using QuickBooks.

It includes the sample invoices, receipts, deposits, and a profit and loss report. The invoices show what was purchased, the total cost of all items, and state the payment terms, including the due date.

These are the receipts, serving as proof of payment, given to the buyer after payment is made. Receipts confirm that payment has been received.

The deposits show that money received from the buyer has been added to the bank account, meaning the payment was received and recorded in the business account.

And here is the profit and loss report for the month of April.