using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication3
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            double d, x, x1, x2, x3;


           x  = Convert.ToDouble(textBox2.Text);
           x1 = Convert.ToDouble(textBox3.Text);
            x2 = Convert.ToDouble(textBox4.Text);
            x3 = Convert.ToDouble(textBox5.Text);

            d = ((8 - x2) / (x - 9)) - ((4 * x1 - 1) / x3);

            textBox1.Text = Convert.ToString(d);
        }
    }
}