Part 1 Ms. Zheng enjoys dinner at a restaurant in Flushing, N. Y.C where the sales tax on meals is 10%. She has the ability to leave a 15% tip on the price of her meal before the sales tax is added, and the tax is calculated on the pre-tip amount. The host at the restaurant was not polite but the bus person was very nice and offered to clean the table before her desert. She spends a total of $27.50 for dinner. What is the cost of her dinner without tax or tip?

Part 2
Ms. Zheng returned to the restaurant the next week. She ordered the same meal and wanted to give an 18% tip because the host was very nice to her this time. What would be the difference in her bill from last week?