How to calculate qty coloumn and price coloumn to update in total coloumn in WPF C#

if (e.Key == Key.Enter)
           {
              // string query = "";
               dataGrid.Focus();

               //dataGrid.CurrentColumn= dataGrid.Columns[2];
               if (txtSearch.Text != "")
               {
                   if (txtSearch.Text != null && txtSearch.Text != "")
                   {
                       //this.DataContext = txtSearch.Text;
                       //dataGrid.ItemsSource = txtSearch.SelectedValue.ToString();
                       DataSet ds = Globalvariables.Globals.select_load("Select menu_id,foodname,rprice from add_food_menu where foodname like '%" + txtSearch.Text + "%'");
                       if (ds.Tables[0].Rows.Count > 0)
                       {
                           for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
                           {
                               string id = ds.Tables[0].Rows[i][0].ToString();
                               string name = ds.Tables[0].Rows[i][1].ToString();
                               string price = ds.Tables[0].Rows[i][2].ToString();
                               string qty = "1";
                               string total = price;
                               //MenuList.Add(new menu(ds.Tables[0].Rows[i][0].ToString(), ds.Tables[0].Rows[i][1].ToString(), ds.Tables[0].Rows[i][2].ToString(), "1"));
                               dataGrid.DisplayMemberPath = "foodname";
                               dataGrid.SelectedValuePath = "menu_id";
                               //dataGrid.ItemsSource = ds.Tables[0].DefaultView;
                               dataGrid.Items.Add(new menu(id = ds.Tables[0].Rows[i][0].ToString(), name = ds.Tables[0].Rows[i][1].ToString(), price = ds.Tables[0].Rows[i][2].ToString(), "1",total));
                               dataGrid.BeginningEdit += (e, ee) => ee.Cancel = true;
                               dataGrid.CurrentCell = new DataGridCellInfo(
                               dataGrid.Items[0], dataGrid.Columns[2]);
                               dataGrid.BeginEdit();
                           }
                           //autoList = MenuList;
                       }
                   }
               }
           }
       }

public class menu : INotifyPropertyChanged
      {
          public static string id;
          public static string name;
          public static string price;
          public static string qty;
          public static string total;

          public menu(string id, string name, string price,string qty,string total)
          {
              this.Id = id;
              this.Name = name;
              this.Price = price;
              this.Qty = qty;
              this.Total = total;
          }
          public string Id
          {
              get { return id; }
              set { id = value; }
          }
          public string Name
          {
              get { return name; }
              set { name = value; }
          }
          public string Price
          {
              get { return price; }
              set { price = value; }
          }
          public string Qty
          {
              get { return qty; }
              set { qty = value;  if (PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("Qty")); }
          }

          public string Total
          {
              get { return (float.Parse(this.Qty) * float.Parse(this.Price)).ToString(); }
              set { total = value; if(PropertyChanged != null) PropertyChanged(this, new PropertyChangedEventArgs("Total")); }
          }

          private void NotifyPropertyChanged(string total)
          {
              if(PropertyChanged != null)
              {
                  PropertyChanged(this, new PropertyChangedEventArgs(total));
              }
          }
          public event PropertyChangedEventHandler PropertyChanged;
          public class UpdateData
          {
              public ObservableCollection<menu> updata { get; set; }
              public UpdateData()
              {
                  updata = new ObservableCollection<menu>();
              }
          }