conversations.from: human
conversations.value: Break down this math problem: Jack wants to send thank you cards to everyone who got him a gift for his wedding.  He sent out 200 invitations.  90% of people RSVPed but only 80% of people who RSVPed actually showed up.  Then 10 people who showed up didn't get a gift.  How many thank you cards does he need?
conversations.from: assistant
conversations.value: He got 200*.9=180 RSVP
  Of those only 180*.8=144 people showed up
  So only 144-10=134 got him gifts and hence need thank you cards.