i get only text (concat(substring-be....) in browser
with:
concat( substring-before(<xsl:value-of
select="prodAmount"/>, '/'), '/',
substring(substring-after(<xsl:value-of
select="prodAmount"/>, '/'), 1, 2))
??

try <xsl:value-of select="concat(substring-before(prodAmount,
'/'),'/', substring(substring-after($x, '/'), 1, 2))

You are trying to apply functions to the xsl elements, which doesn't
work.  It just treats it as literal text and passed through to the
browser.

Jon G.