conversations.from: human
conversations.value: Kim orders a $10 meal and a drink for 2.5.  She gives a 20% tip.  She pays with a $20 bill.  How much does she get in change?
  Find the solution.
conversations.from: assistant
conversations.value: The dinner cost 10+2.5=$12.5.
  The tip comes to 12.5*.2=$2.5.
  So the total cost is 12.5+2.5=$15.
  That means she gets 20-15=$5 in change.