About: http://webisa.webdatacommons.org/446444823

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	you will need to write on of these for both textboxes, and on leave I would check to make sure that the value is a number before performing the addition of the 2 values.
http://www.w3.org/ns/prov#wasQuotedFrom	codeproject.com