I need some help in my Java Assignment which is a simple program for managing phonecall

abstract class PhoneCall
{

    String phoneNumber;
    double price;

     PhoneCall(String phoneNumber)
    {
        this.phoneNumber =  phoneNumber;
        this.price = 0.0;
    }
    public String getPhoneNumber() {
        return phoneNumber;
    }

    public double getPrice() {
        return price;
    }

    public abstract void setPrice();

}
class IncomingPhoneCall extends PhoneCall {

    final static double RATE=0.02;
     IncomingPhoneCall(String phoneNumber){
        super(phoneNumber);
        setPrice();
    }
    public void setPrice() {
        price = 0.02;
    }
     void info(){
        System.out.println("Incoming phone call"+getPhoneNumber()+
                " "+RATE+" per call.Total is $"+getPrice());
    }
      public String getPhoneNumber()
      {
          return phoneNumber;
      }
      public double getPrice()
      {
          return price;
      }

}
class OutgoingPhoneCall extends PhoneCall {

    final static double RATE = 0.04;
    private int minutes;
     OutgoingPhoneCall(String phoneNumber, int minutes){
        super(phoneNumber);
        this.minutes = minutes;
        setPrice();;
    }
    public void setPrice() {
        price = 0.04;
    }
    void info() {
        System.out.println("Outgoing phone call " + getPhoneNumber() + " "
                + RATE + " per minute at " + minutes + " minutes. Total is $" + price*minutes);
    }
     public String getPhoneNumber()
     {
         return phoneNumber;
     }
     public double getPrice()
     {
         return price;
     }

}


public class DemoPhoneCalls {
public static void main(String [] args) {

    IncomingPhoneCall incomingPhoneCall=new IncomingPhoneCall("310-332-0908");
    OutgoingPhoneCall outgoingPhoneCall=new OutgoingPhoneCall("310-000-0102",20);

    incomingPhoneCall.info();
    outgoingPhoneCall.info();
 }
}