Uncle Harry Lupine has six passes to an amusement park. Some of the passes are day passes, which cost $ 10, and the rest are season passes, which cost $ 28. Uncle Harry paid a total of $ 78 for all passes. Lenore and Freddy decide to systematize equations to calculate the number of daily passes and season passes they have. Which of the following are good choices for variables to use to model this situation? Select all that apply.