Here is a code snippet for you:
using System;
using System.Linq;
using System.Xml.Linq;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
string xml = "<Calendar/>";
XElement calendar = XElement.Parse(xml);
var query = from rday in calendar.Descendants("Rday")
where rday.Attribute("number").Value == "20"
select (string)rday.Element("Description").Attribute("text");
foreach (var text in query)
{
Console.WriteLine(text);
}
}
}
}