Mrs. White likes shopping. Today is Sunday. She wants to buy a new dress for herself. Now she is in a clothes store and has a look at a red one. She asks the salesgirl , "How much is it?" "It's thirty dollars." the salesgirl answers. "Can I _ , please?" she asks. "Yes, you can. The dressing room is over there. This way, please." the salesgirl says. After Mrs White comes out of the dressing room, the salesgirl says to her, "You look ten years younger  in this red dress." Hearing  that, Mrs. White says, "I will not take the dress, because I don't want to look ten years older  after I take off  the dress." How much is the dress?
40 dollars. 15 dollars. 50 dollars. 30 dollars.