Adding calculations to XDO_METADATA worksheet

EBS 12.2

I want to add a calculation to an excel template on the XDO_METADATA worksheet but so far all the ways I've tried to do it have been unsuccessful.

To start with I'm trying to multiple the value in one column by a value in another column.

The syntax for my latest attempt is :-

<?xsl:value-of select ="(//RATE) *(//CONTRACT_HRS)"?>

I've tried:-

<?xsl:value-of select ="(.//RATE) *(.//CONTRACT_HRS)"?>

<?xsl:value-of select ="(RATE) *(CONTRACT_HRS)"?>

Can anyone point me in the right direction?

I'm not using BI publisher for the build.

Thank you!