Anna enjoys dinner at a restaurant in Washington, D.C., where the sales tax on meals is 10 \%. She leaves 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. She spends a total of \$ 27.50 for dinner. What is the cost of her dinner without tax or tip?
Answer Choices
A. \$ 18
B. \$ 20
C. \$ 21
D. \$ 22
E. \$ 24