ASP.Net: Calculate Field value in ASPX page

This code works 100%, it was written by our teacher Muddassar

I would like to list the ctrypopulation variable value that I added to the table and the ctrymultiply value that I added to the table, and the country's population increase as a percentage, in a circular manner. Best regards, my great teacher.

<div>
    <table>
        <% foreach (var c in this.item())
            { %>
        <tr>
            <td>
                <label><%=c.countryid%></label></td>
            <td>
                <input type="text" value='<%=c.countryname %>' /></td>
            <td>
                <input type="text" value='<%=c.photo%>' /></td>
            <td>
                <input type="radio" <%=c.countryname.ToLower() == "india" ? "checked" : "" %> /></td>
            <td>
                <input type="checkbox" <%=c.countryname.ToLower() != "india" ? "checked" : "" %> /></td>
            <td>
                <a href='Details.aspx?idno=<%=c.countryid %>'>Customer Detail</a> </td>
            <td>
                <button type="submit" name="btnSubmit_<%=c.countryid%>">View</button>
            </td>
        </tr>
        <% } %>
    </table>
</div>
<hr />
<div>
    <table>
        <tr>
            <td>
                <label><%=countryidx%></label>
            </td>
        </tr>
        <tr>
            <td>
                <input type="text" value='<%=ulkeismix%>' />
            </td>
        </tr>
        <tr>
            <td>
                <input type="text" value='<%=photox%>' />
            </td>
        </tr>
    </table>
</div>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page
{
    public int ctryresult;
    public int countryidx;
    public string photox;
    public string ulkeismix;

    public List<Country> item()
    {
        string sqlStatment = "select * from Country";
        string constr = System.Configuration.ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
        using (System.Data.SqlClient.SqlConnection con = new System.Data.SqlClient.SqlConnection(constr))
        {
            using (System.Data.SqlClient.SqlCommand cmd = new System.Data.SqlClient.SqlCommand(sqlStatment, con))
            {
                cmd.Connection.Open();
                System.Data.SqlClient.SqlDataReader reader = cmd.ExecuteReader();
                List<Country> emp = new List<Country>();
                while (reader.Read())
                {
                    Country country = new Country();
                    country.countryid = Convert.ToInt32(reader.GetValue(0));
                    country.countryname = reader.GetValue(2).ToString();
                    country.photo = reader.GetValue(1).ToString();

                    country.ctrypopulation = reader.GetValue(3).ToString();

                    country.ctrymultiply = reader.GetValue(4).ToString();

                    emp.Add(country);
                }

                reader.Close();
                cmd.Connection.Close();
                return emp;
            }
        }
    }

    public class Country
    {
        public int countryid { get; set; }
        public string countryname { get; set; }
        public string photo { get; set; }
    }

    public List<Country> Item { get; set; }
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!this.IsPostBack)
        {
            this.Item = this.item();
        }
        else
        {
            foreach (string item in Request.Form.AllKeys)
            {
                if (item.Contains("btnSubmit"))
                {
                    string id = item.Split('_')[1].Trim();
                    string sqlStatment = "SELECT * FROM country WHERE countryid=@Id";
                    string constr = System.Configuration.ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
                    using (System.Data.SqlClient.SqlConnection con = new System.Data.SqlClient.SqlConnection(constr))
                    {
                        using (System.Data.SqlClient.SqlCommand cmd = new System.Data.SqlClient.SqlCommand(sqlStatment, con))
                        {
                            cmd.Parameters.AddWithValue("@Id", id);
                            cmd.Connection.Open();
                            System.Data.SqlClient.SqlDataReader reader = cmd.ExecuteReader();
                            if (reader.Read())
                            {
                                countryidx = Convert.ToInt32(reader.GetValue(0));
                                ulkeismix = reader.GetValue(1).ToString();
                                photox = reader.GetValue(2).ToString();
                            }

                            reader.Close();
                            cmd.Connection.Close();
                        }
                    }
                    break;
                }
            }
        }
    }
}

i adds line begin web designer side

<td>
    <input type="text" value='<%=c.ctrypopulation%>' /></td>
<td>
<td>
    <input type="text" value='<%=c.ctrymultiply%>' /></td>
<td>
 <td>
    <input type="text" value='<%=c.ctryresult%>' /></td>
<td>
 <td>
    <input type="text" value='<%=ctryresult=%>'=<%=c.ctrymultiply%* <%=c.ctryresult%>  /></td>
<td>