Ingrid has been waiting for the show "Mamma Mia!" to come to town. When it finally does come, ticket prices are $60. Ingrid's reservation price is $75. But when Ingrid tries to buy a ticket, they are sold out. Ingrid decides to try to buy a ticket from a scalper (a person who has purchased extra tickets at the box office with the intent to resell those tickets). If Ingrid finds someone who is willing to sell her a ticket for $70, she should