conversations.from: human
conversations.value: Find a solution for this math problem: James needs to get a new pair of glasses.  His frames cost $200 and the lenses cost $500.  Insurance will cover 80% of the cost of lenses and he has a $50 off coupon for frames.  How much does everything cost?
conversations.from: assistant
conversations.value: He gets 500*.8=$400 off the cost of lenses
  That means the lenses cost 500-400=$100
  The frames cost 200-50=$150
  So he pays 100+150=$250