Having FormulaR1C1 Result in a Function

All variables represent a column that contains dates.

Is there a way to make this function result in a different function if true? The function I would like it to result in is the date in variable9 + 30 days.

I'm new to the FormulaR1C1 style, so I'm a little stuck with this one. Thanks for taking a look.

    .FormulaR1C1 = "=IF(AND(RC" & variable9 & "<>0,RC" & variable9 & " > RC" & variable10 & "), "=" & variable9 & " "+30"",FALSE)"

Moderator's Edit: This thread is not a duplicate.