Sophia wrote an equation to represent the revenue of a movie theater for one day. she let x represent the number of child tickets sold and y represent the number of adult tickets sold. if a child ticket costs $4, an adult ticket costs $6, and the total revenue for the day was $420, which equation could sophia use to represent the number of child and adult tickets that were sold? mc009-1.jpg mc009-2.jpg mc009-3.jpg mc009-4.jpg