conversations.from: human
conversations.value: Lucy lost one-third of her money. She then spent one-fourth of the remainder, and only left with $15. How much money did Lucy have at the beginning?
  Solve it.
conversations.from: assistant
conversations.value: The $15 is 1 - 1/4 = 3/4 of the money left.
  Since 3/4 is equal to $15, then 1/4 is equal to $15/3 = $5.
  So Lucy had $5 x 4 = $20 left after losing 1/3 of her money.
  Hence, $20 is 1 - 1/3 = 2/3 of the money that Lucy had at the beginning.
  Since 2/3 is equal to $20, then 1/3 is equal to $20/2 = $10.
  Therefore, Lucy had $10 x 3 = $30 at the beginning.