please draw system flowchart!

Delta Ltd sells and installs solar panels. Their main customer base is homeowners but they also occasionally do a large industrial installation. The billing process for Delta is described below. Once an installation date has been confirmed, the Installation Team Leader prepares and sends a completed Confirmed Installation form to Accounts Receivable. The Billing Officer enters the details into the computer, which saves the sales order data and prints two copies of an invoice. The Billing Officer collects the printed invoices from the computer print room and sends them to the Installation Team Leader. The Installation Team Leader checks the details and posts one copy of the invoice to the customer. As all installation invoices must be paid in full before the installation takes place, the installation request form is matched to the invoice and the matched documents are filed in customer number order in the Awaiting payment file.