conversations.from: human
conversations.value: Break down this math problem: Carly had 80 cards, 2/5 of the cards had the letter A on them, 1/2 of the remaining had the letter B, 5/8 of the rest had the letter C on them, and the others had the letter D. How many of the cards had the letter D on them?
conversations.from: assistant
conversations.value: The number of cards with the letter A on them is 2/5*80 = 32 cards.
  There were 80-32 = 48 cards with no letter on them.
  Half of the remaining cards had the letter B on them, a total of 1/2*48 = 24 cards.
  Out of the remaining cards, the number that did not have the letter B on them is 48-24 = 24
  If 5/8 of the remaining cards had the letter C on them, there were 5/8*24 = 15 cards with the letter C on them.
  The number of cards that had the letter D on them is 24-15 = 9