cong 2 phan so

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ktlt
{
    class Class5
    {
        struct PhanSo
        {
            public int TuSo;
            public int MauSo;
        }
        static PhanSo NhapPhanSo(string ghichu)
        {
            Console.WriteLine(ghichu);
            PhanSo kq;
            Console.WriteLine("nhap tu so");
            kq.TuSo = int.Parse(Console.ReadLine());
            Console.WriteLine("nhap mau so");
            kq.MauSo = int.Parse(Console.ReadLine());
            return kq;
        }

        static PhanSo Cong2PS(PhanSo a, PhanSo b)
        {
            PhanSo kq;
            kq.TuSo = a.TuSo * b.MauSo + a.MauSo * b.TuSo;
            kq.MauSo = a.MauSo * b.MauSo;
            //Console.Write(kq);
            return kq;
        }

        static string XuatPhanSo(PhanSo kq)
        {
            return string.Format("{0}/{1}", kq.TuSo, kq.MauSo);
        }

        static void Main(string[] args)
        {
            PhanSo a, b;
            a = NhapPhanSo("nhap phan so a");
            b = NhapPhanSo("nhap phan so b");
            PhanSo kq=Cong2PS(a, b);

            string chuoi = "ket qua la " + XuatPhanSo(kq);
            Console.WriteLine(chuoi);
            Console.ReadLine();
        }
    }
}