How to use AND operator in XPath?

Question

XML is like

 
   value1
   value2
 

I want to write XPath to find id of <

Answer 1

The following XPath,

//a[b = 'value1' and b = 'value2']/@id

will select id attributes of all a elements with a child b element having string value equal to value1 AND another child b element having string value equal to value2 as requested.