conversations.from: human
conversations.value: Explain how to solve this math problem: Mary used 15 gallons of fuel this week. Last week she used 20% less. How much fuel did she use in total for the two weeks?
conversations.from: assistant
conversations.value: Last week, she used 15 gallons * 0.2 = 3 gallons less fuel than she used this week.
  This means that she used 15 gallons – 3 gallons = 12 gallons of fuel last week.
  In total, Mary used 15 gallons + 12 gallons = 27 gallons of fuel.