using System;

​

public class Program

{

    public static void Main()

    {

        var product = new Product{Price = 10000};

        Console.WriteLine(product.Price);

        Console.WriteLine(product.Discount());

        Console.WriteLine(product.Price);

        Console.WriteLine(product.Price - product.Discount());

    }

}

​

public class Product

{

    public decimal Price

    {

        get;

        set;

    }

}

​

//This is extension class

public static class MyExtensions

{

    //this is extension method

    public static decimal Discount(this Product product)

    {

        return product.Price * .09M;

    }

}