conversations.from: human
conversations.value: Jean is two years older than Mark.  Two years ago Mark was 5 years older than half Jan's age.  If Jan is 30 how old is Jean?
  How to solve this?
conversations.from: assistant
conversations.value: 2 years ago Jan was 30-2=28 years old
  So Marks age two years ago was 5+28/2=19 years old
  Mark is now 19+2=21 years old
  So Jean is 21+2=23 years old