How to add date in TEXT type with REAL type

I am trying to add a Date field which is of type TEXT with 2 fields of type REAL and with the result I have to compare with current date in SQLite. But I am stuck in adding TEXT and REAL to get the calculated date.

i.e. I have 2005-10-01 in TEMP_DATE Field and 15.0 and 4.0 in THRESHOLD1 and THRESHOLD2 respectively. I have to add these 3 fields to get result as 2015-10-20.