How much does one T-shirt cost?

W: I’d like to buy a T-shirt. But will I save any money if I buy a pair?
M: Yes. If you buy one, you have to pay six dollars, but you can have two of them for ten dollars.

W: Are you sure you can’t stay any longer? The others are not leaving yet, you know.
M: No, I’m afraid I must go, but thank you very much indeed for a most enjoyable evening, and a wonderful dinner.