Develop a system level data flow diagram (DFD) for the systems described in the following business narratives. Show all data flows, data stores and external entities. If you discover that the narrative is incomplete, you can make assumptions to complete the story. Note these additional assumptions along with the diagram.

Perfect Pizza wants to install a system to record orders for pizza and chicken wings. When regular customers call Perfect Pizza on the phone, they are asked their phone number. When the number is typed into a computer, the name, address, and last order date is automatically brought up on the screen. Once the order is taken, the total, including tax and delivery, is calculated. Then the order is given to the cook. A receipt is printed. Occasionally, special offers (coupons) are printed so the customer can get a discount. Drivers who make deliveries give customers a copy of the receipt and a coupon (if any). Weekly totals are kept for comparison with last years performance.