using System;

public class Program

{

    public static void Main()

    {

        var product = new Product 

        {

            Price = 10, 

            IsFragile = true, 

            IsOverWeight = true, 

            IsExpensive = true

        };

        Console.WriteLine(Helper.Shipping(product, 5, "FedEx"));

    }

}

​

public class Product

{

     public decimal Price { get; set; }    

     public bool IsFragile { get; set;}

     public bool IsOverWeight { get; set;}

     public bool IsExpensive { get; set;}

}

​

public static class Helper

{

     public static decimal Tax(Product product, string shippingMethod)

     {

          if (shippingMethod == "FedEx") return 0.1m;

          if (shippingMethod == "DHL") return 0.15m;

          if (shippingMethod == "Free") return 0;         

          return 0;

     }

     public static decimal Shipping(Product product, decimal expensiveLimit, string shippingMethod)

     {

          decimal c;         

          switch(shippingMethod)

          {

               case "FedEx":

                    c =  product.Price * 0.1m; // 0.1 tax

                    if (product.IsFragile)

                         c = c + 100m;

                    if (product.IsOverWeight)

                         c = c + 200m;

                    break;              

               case "DHL":

                    c =  product.Price * 0.25m; // 0.25 tax

                    if (product.IsFragile)

                         c = c + 150m;

                    if (product.IsOverWeight)

                         c = c + 350m;

                    break;    

               case "Free":

                    c = product.Price;

                    break;

               default:

                    return 0;

          }

          // Reuse the calculated shipping cost and check if the product is expensive

          product.IsExpensive = c > expensiveLimit;

          return c;

     }

}