I think you are looking for ToText(CCur(@Price}/{ValuationReport.YestPrice}*100-100))
You can use CCur
to convert numbers or string to Curency formats. CCur(number)
or CCur(string)
I think this may be what you are looking for,
Replace (ToText(CCur({field})),"$" , "")
that will give the parentheses for negative numbers
It is a little hacky, but I'm not sure CR is very kind in the ways of formatting