三、簡答題（共 8 分）
Sarah drinks 10 coffees and eats 4 cakes a week. Coffees are $2 each and cakes are $5 each. This week, the government placed a tax on coffees and the price doubled to $4, but at the same time, the income tax has been revised so that Sarah's budget has increased as well. She can now just afford her usual 10 coffees and 4 cakes a week. Does Sarah better off this week than last week? Explain with a figure.