People between the ages of 21 and 35 are surveyed. the mean of their credit card debt is $12,388. suppose the mean credit card debt for this age group is $9301. ( the picture where it says "what is" is the what i'm trying to find

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 represents the nunver of adult tickets sold. if a child ticket cost $4, an adult ticket cost $6, and the total revenue for the daybwas $420, which equation could sophia use to represent the number of chikd and adult tickets that were sold?