身边的经济学·社会常识英语30篇（2）

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预算约束线与消费组合选择

With $50 a week for food and transport, you can’t buy unlimited takeout *and* subway passes *and* fresh fruit.
Every choice has a trade-off: one more coffee means one less snack—or skipping lunch twice.
Prices set the slope of your budget line—when bus fare rises, your food options shrink unless income grows.
Students often redraw this line weekly: 'Can I afford both Netflix *and* textbooks this month?'
Sales and coupons shift the line outward temporarily—but real flexibility comes from steady income or lower fixed costs.
Seeing choices as points along a line—not isolated yes/no decisions—builds clearer spending habits.
Apps that track spending help visualize where you sit on that line each day.
Parents teaching teens often use allowance + chores to model this trade-off early.
It’s not about restriction—it’s about mapping what matters *most* within real limits.
Freedom lies in conscious trade-offs—not endless options.