Your friend decides to leave school so that they can earn more income by working more hours at their job. Some years later, you run into them, and they tell you about a promotion they missed out on due to not having a degree. Which of the six core principles of the economic way of thinking does this illustrate? People Gain When There is Voluntary Trade Economic Systems Influence Choices and Incentives People Respond in Predictable Ways to Incentives. The Consequences of Choices Lie in the Future