For the next four problems, consider the task of representing types of tickets to campus events. Each ticket has a unique number and a price. There are three types of tickets: walk-up tickets, advance tickets, and student advance tickets. Figure 9.10 illustrates the types:

• Walk-up tickets are purchased the day of the event and cost $50.

• Advance tickets purchased 10 or more days before the event cost $30, and advance tickets purchased fewer than 10 days before the event cost $40.

• Student advance tickets are sold at half the price of normal advance tickets: When they are purchased 10 or more days early they cost $15, and when they are purchased fewer than 10 days early they cost $20.

Implement a class called Ticket that will serve as the superclass for all three types of tickets. Define all common operations in this class, and specify all differing operations in such a way that every subclass must implement them. No actual objects of type Ticket will be created: Each actual ticket will be an object of a subclass type. Define the following operations:

• The ability to construct a ticket by number.

• The ability to ask for a ticket’s price.

• The ability to println a ticket object as a String. An example String would be "Number: 17, Price: 50.0".