1. If all consumers are price-takers facing the same prices, then their budget lines will all have the same slope.
2. If all consumers are price-takers facing the same prices, then all choice sets are the same.
3. Regardless of which consumption bundle in her choice set a consumer chooses, she will spend all of her available income.
4. Kinks in budget constraints always produce non-convexities in choice sets.
5. The only way for a consumer choice set to be non-convex is for the budget line to be kinked.
6. When the good on the vertical axis is a composite good, the slope of the budget line is equal to minus the price of the good on the horizontal axis.
7. When the good on the horizontal axis is a composite good, the slope of the budget constraint is minus the price of the good on the vertical axis.
8. While the endowment bundle must lie on the original budget line, it need not lie on the budget line when prices change.