title: Calculate how many years there's left on a debt and print it in date format
body: <p>I'm using Google Docs Spreadsheet and I want to calculate how many years there is left on a debt from a fixed date (YYYY-MM-DD), into a date (same formation).</p>
  
  <p>Example: I started to pay off on a debt which are on 20 000, 2014-03-31. Every month, I'll pay 200 and the debt will be payed off 2022-03-31. If I change the pay sum (200) to another sum, the date will be based on the new sum and change the final debt year.</p>
  
  <p>How can I accomplish this?</p>