conversations.from: human
conversations.value: Solve the math problem: Martin has 18 goldfish. Each week 5 goldfish die. Martin purchases 3 new goldfish every week. How many goldfish will Martin have in 7 weeks?
conversations.from: assistant
conversations.value: In 7 weeks 5*7 = 35 goldfish die.
  In 7 weeks, Martin purchases 3*7 = 21 goldfish.
  In 7 weeks, Martin will have 18-35+21 = 4 goldfish.