Hi Caridad
Thanks, the calculation is working now! I just have this problem now with this error message appearing on the page the modal is loading from. I'm loading that view inside a modal.
Parse error: syntax error, unexpected '*' in /functions.php(187) : eval()'d code on line 1
(Line 187 is your line 4)
When I remove the * operation and just have the minus I get this error.
Parse error: syntax error, unexpected ';' in /functions.php(187) : eval()'d code on line 1
It seems to be having a problem with the symbols for the calculation used inside the view.