This example code will convert specific part of xml to plaintext using XmlTransform alias.
 string xsl = @"<xsl:stylesheet version=""1.0"" xmlns:xsl=""http://www.w3.org/1999/XSL/Transform"">
   <xsl:output method=""text"" omit-xml-declaration=""yes"" indent=""no""/>
   <xsl:strip-space elements=""*""/>
   <xsl:template match=""pastery/cake""><xsl:value-of select=""@price""/></xsl:template>
 </xsl:stylesheet>";

 string xml = @"<?xml version=""1.0"" encoding=""UTF-8""?>
 <pastery>
     <cake price=""1.62"" />
 </pastery>";

 var text = XmlTransform(xsl, xml, new XmlTransformationSettings {
     ConformanceLevel = System.Xml.ConformanceLevel.Fragment, Encoding = Encoding.ASCII });