Inheritance - override & virtual

//In Bicycle.cs file
using System;

namespace LearnInheritance
{
  class Bicycle : Vehicle {
    public Bicycle(double Speed): base(Speed){
      Wheels =2;
    }

    //use override keyword to override parent/superclass methods
    public override void SpeedUp(){
      Speed +=5;
      if (Speed >15) {
         Speed = 15;
      }
    }
    public override void SlowDown(){
      Speed -=5;
      if (Speed<0){
        Speed =0;
      }
    }

  }
}
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//In Vehicle.cs file
using System;

namespace LearnInheritance
{
  class Vehicle
  {
    public string LicensePlate
    { get; private set; }

    public double Speed
    { get; protected set; }

    public int Wheels
    { get; protected set; }

    public Vehicle(double speed)
    {
      Speed = speed;
      LicensePlate = Tools.GenerateLicensePlate();
    }

    //mark the methods with virtual keyword so as to allow child/subclass to override it
    public virtual void SpeedUp()
    {
      Speed += 5;
    }

    public virtual void SlowDown()
    {
      Speed -= 5;
    }

    public void Honk()
    {
      Console.WriteLine("HONK!");
    }

  }
}