14th January 2011 (Friday)
1. January 15th, 2011 (Saturday)
2. January 16th, 2011 (Sunday)
3. January 17th, 2011 (Monday)
4. January 18th, 2011 (Tuesday)
5. January 19th, 2011 (Wednesday)
6. January 20th, 2011 (Thursday)
7. January 21st, 2011 (Friday)
Add 84 days to January 21st, 2011
1. January 22nd (Saturday)
2. January 23rd (Sunday)
3. January 24th (Monday)
4. January 25th (Tuesday)
5. January 26th (Wednesday)
6. January 27th (Thursday)
7. January 28th (Friday)
Add 84 days to January 28th, 2011
1. January 29th (Saturday)
2. January 30th (Sunday)
3. January 31st (Monday)
4. February 1st (Tuesday)
5. February 2nd (Wednesday)
6. February 3rd (Thursday)
7. February 4th (Friday)
So, 84 days from January 14th, 2011, will be a Friday, which is April 15th, 2011.