Esperanza is determining whether she has enough money to buy a pizza and still tip the delivery person. The pizza costs $15 plus 7.5% sales tax, and Esperanza wishes to tip twice the amount of the sales tax. She has only a $20 bill. She also remembered that Pizza the Hut recently added a $1.50 delivery fee. What is the amount of tax? What is the amount of tip? Explain why she does or does not have enough money.