using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {       

​

        decimal? PldCommissionBasicDisc = null;

        var result =  5 + PldCommissionBasicDisc ?? 0;

        Console.WriteLine("Result= " + result);

    }

}

​

public class CommissionBasic

{

    public int Value;   

    public int PldCommissionBasicDisc;

}