I want to know when romantic relationships began. I have three different variables that indicate how long respondents have been in their relationships (they indicate how many years, days, and months they've been in their relationships). I want to get an actual date for the beginning of the relationship, rather than knowing how long they've been in their relationships. However, I do know the date respondents were interviewed. Is there a way to figure out a date for the beginning of the relationship if I know their interview date?