两个值相乘，用xpath如何表示？
计算<price>跟<availability>两个值相乘，用xpath如何表示？
<?xml version="1.0" encoding="iso-8859-1"?><catalog xmlns="urn:mycompany:examples:plants"><plant><common>Bloodroot</common><botanical>Sanguinaria canadensis</botanical><zone>4</zone><light>Mostly Shady</light><price>2.44</price><availability instock="yes">100</availability></plant></catalog>
