Required date using selected date plus selected days

Question

I'm using jQuery Datepicker for Selected Date & DropDownList for Selected Days(i.e. 7 to 15 days )
How to get the Required date which include selected date plus Selected Days
i.e Selected Date =25-Oct-2014 & Selected Days=10
Then Required Date=04-Nov-2014

How to get that Required date in Page_Load Event