The height of a building is proportional to the number of floors. If the building is 135 ft with 9 floors, how many floors does this build have? How tall would the building be if it had 15 floors?

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?