C#调用cplex 提问

诚意问 C#调用cplex如何描述变量间的关联约束 例如 变量1.变l2=变量3

using ILOG.CPLEX;
using System;

namespace CplexDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                Cplex cplex = new Cplex();

                INumVar x = cplex.NumVar(0, double.MaxValue, "x");
                INumVar y = cplex.NumVar(0, double.MaxValue, "y");

                ILinearNumExpr expr = cplex.LinearNumExpr();
                expr.AddTerm(1.0, x);
                expr.AddTerm(2.0, y);
                cplex.AddLe(expr, 10.0);

                ILinearNumExpr objExpr = cplex.LinearNumExpr();
                objExpr.AddTerm(3.0, x);
                objExpr.AddTerm(4.0, y);
                cplex.AddMaximize(objExpr);

                cplex.Solve();

                Console.WriteLine("Solution status = " + cplex.GetStatus());
                Console.WriteLine("Solution value = " + cplex.ObjValue);
                Console.WriteLine("x = " + cplex.GetValue(x));
                Console.WriteLine("y = " + cplex.GetValue(y));
            }
            catch (ILOG.Concert.Exception ex)
            {
                Console.WriteLine("Error: " + ex.Message);
            }
            Console.ReadKey();
        }
    }
}