Issue with subtracting two values

I am trying to subtract one value that is a calculated field in the form, Total Hrs
Potential Savings (the product of two fields in the document). Annual Leave
Hours is an entered field. I used the Simplified field notation option:

Total\ Hrs\ Potential\ Savings-Annual\ Leave\ Hours but it is not calculating. I tried with and without spaces around the minus sign. I don’t know anything about writing
java scripts. I am using Adobe Acrobat XI, version 11.0.2.

Thanks!