Can't get subtraction to work in variable statement

For some reason, the first two variable declarations work fine, but the
third one gives this error:
pattern = '$pm-$hourMinutes' Extra illegal tokens: '$', 'hourMinutes'

     <xsl:variable name="hours" select="round($pm div 60)"/>
     <xsl:variable name="hourMinutes" select="$hours*60"/>
     <xsl:variable name="minutes" select="$pm-$hourMinutes"/>

Can't I subtract in XSL? I'm using Xalan.

--

Brian N. Burridge
Internet Architect
(727) 399-3000 Ext 3515
The Internet Group - ITSS
Cox Target Media

"Until a person can say deeply and honestly, "I am what I am today
because of the choices I made yesterday," that person cannot say, "I
choose otherwise."



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