conversations.from: human
conversations.value: This math problem has got me stumped: John decided to buy 10 pins for himself.  They are normally $20 each but they were on sale for 15% off.  How much did he spend on pins?
  Can you show me the way?
conversations.from: assistant
conversations.value: The sell reduced the price of each pin by 20*.15=$3
  So he paid 20-3=$17 per pin
  So the total cost was 17*10=$170