Problem adding days to a date using DATEADD

I am trying to pass a stored procedure a variable that allows the user to specify how may days should be added to the date. I am getting an error since I'm not 100% sure how I need to declare the variable I am using int currently and the date add function look like:

DATEADD(dd, ' + @DaysToadvnce + ', ''' + cast(@today as nvarchar(50)) + '''))

the actual query is a string also. Any help would be much appreciated, Thanks.

I figured out what I needed to do:

DATEADD(dd, ' + cast(@DaysToadvnce as nvarchar(50) + ', ''' + cast(@today as nvarchar(50)) + '''))