Scenario to ERD

A bus company wants to keep track of its bus routes and schedules. Design an ER diagram for the database according to the following description. Identify all constraints and keys: Each bus route has a route number, a departure station and a destination station. For each bus route, there is a schedule, which records the departure times of buses. For each departure time of each route, a driver and a bus can be assigned (however this is not necessary - information about the driver or the bus may sometimes be missing). A driver has an employee Id, a name and a phone number. A bus is identified by its license number. The database also records the seating capacity of each bus.