Chapter 10, Problem 4FTE

// Superclass

  public class Vehicle

  {

    public abstract double getMilesPerGallon( );

   (Other methods …)

  }

  // Subclass

  public class Car extends Vehicle

  {

   private int mpg;

   public int getMilesPerGallon();

   {

     return mpg;

   }

   (Other methods…)

  }