conversations.from: human
conversations.value: Anna has 50 pencils and Harry has twice the number of Anna’s Pencils but he lost 19 of them. How many pencils are left with Harry?
  Give me a clear explanation.
conversations.from: assistant
conversations.value: The number of Harry’s pencils is 50 * 2 = 100 pencils.
  The number pencils left is 100 – 19 = 81 pencils.