In 2001, there were 68,490,000 households in the United States subscribing to cable television ser-
vices. Round this number to the nearest million.
(Source: Nielsen Media Research-NTI)

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?