Tom's mother is in the shopping mall now. She buys a dress for herself. It is not cheap. It costs her $150. She buys a new backpack for Tom. It is $40. Tom's father needs a new shirt. There are many kinds of shirts. Tom's mother can't make up her mind. So she calls Tom's father and asks, "What color do you prefer?" "I prefer light blue," Tom's father answers. It costs her $70.