A: Do you want to come with me to Walmart?
B: What do you need to buy?
A: I'm out of groceries.
B: Groceries are expensive at Walmart!
A: You really think so?
B: Yes! You should buy groceries at the market.
A: I also need some new blankets.
B: Well, you'd buy that at Walmart.
A: If Walmart sells both, why go to different stores?
B: You'll save money if you do.
A: Why will I save money by going to different stores?
B: Stores have different prices for different things.