It helps me to make a relation entity model with barker notation of the following problem.

PROBLEM In the Company "Educacin Para Avanzar S.A." control of your Goods and Services is kept. The primary interest is to be able to have the Goods handled quickly and with the least degree of error. For this, whoever manages the "Supplies" section raises the following business conditions for the construction of a database: The Section is divided into three (3) areas: PURCHASES, WAREHOUSE, INVENTORY. The Purchasing area works as follows: Receive purchase requests from different areas of the company. Each request has a person in charge. Each request is authorized by the head of the area and later by the Financial Director. Whoever makes a request may be responsible for one or more cost centers, with the exception that he as an employee is only assigned to one. The following information must be filled out in the application: Application number (consecutive), Date, Person in charge (name and ID), Cost Center, Budget item from which the purchase will be downloaded. In each request, one or many items can be distinguished with the following information: item, name of the good, quantity requested, unit of measurement of the good, unit value and total value. Each request must be totalized. Each asset is identified by a universal code that is unique and is of a return nature (supply) or real estate. Once the request is completed, it is sent to the purchasing area to make its corresponding quote. The quotes are made with one or more suppliers of the requested goods. Once the final quote is ready, a contractual order is created that handles the following information: Number of the contractual order, Nit and name of the supplier from whom the purchase is to be made, date of the order, total amount of the order, delivery date. Each order can have one or more items associated with the request or requests to be dispatched. Each item has the following information: name of the good, quantity requested, quantity dispatched, unit of measure of the good, unit value and total value. The purchase order is approved by the Chief Financial Officer to be sent to the chosen supplier.

The Warehouse area works as follows: Its main function is to receive the goods that arrive from the suppliers and distribute them to the corresponding areas that made the purchase requests. When a merchandise supplier arrives, it makes a physical delivery of the goods, which are compared with the invoice that is delivered and with the corresponding purchase order. If this action is correct, a warehouse entry is recorded for each related invoice, with the following information: Entry Number, Date, Invoice Number, Supplier, Total Goods, Total Value (the totals must match those of the invoice). Attached to this are the items received with the following information: o name of the good, quantity delivered. When the warehouse decides to dispatch the goods to the different requesting areas, it registers each of the deliveries in Warehouse Outlets with the following information: Exit Number, Employee responsible for the good to be delivered, departure date, delivery date. For each delivery, each item is detailed with the following information: name of the good, quantity delivered. A warehouse entrance can generate many warehouse exits, for example: 500 bales of toilet paper can enter, but since it must be distributed among several areas, each one requires a warehouse exit. The inventory area works as follows: It is in charge of managing and controlling the location of the goods within the company, for this reason before the good leaves the warehouse it must be encoded through a unique code that makes it identifiable within the company. The location of the property is identified by the following information: responsible for the property, date of delivery, address of the property (location).