conversations.from: human
conversations.value: John decides to start collecting art.  He pays the same price for his first 3 pieces of art and the total price came to $45,000.  The next piece of art was 50% more expensive than those.  How much did all the art cost?
conversations.from: assistant
conversations.value: The first 3 pieces each cost 45000/3=$15,000
  So the next piece was 15,000*.5=$7,500 more expensive
  That means it cost 15,000+7,500=$22,500
  That means in total he spent 45,000+22,500=$67,500