[xsl] maths operations with xslt

[Juan Perez <juan.perez@xxxxxxxxxx>]

hi,

given this numeric value got from the xml file, 

<xsl:value-of select="//Population_infos/Population_info[0]/Population"/>
(this data is well seen in the display)

I want to operate it, for example, adding 5 or 

<xsl:value-of
select="//Population_infos/Population_info[0]/Population+//Population_infos/
Population_info[1]/Population"/> 

to have the sum of this two numbers.

The error message I receive is the next one:

Expected token 'eof' found '+'.
//Population_infos/Population_info[0]/Population-->+<--//Population_infos/Po
pulation_info[0]/Population

Does anybody know how to solve this matter?

Thanks in advance,

Juan

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