please and thank you quick

At the newest animated movie, for every 9 children, there are 4 adults. there are a total of 39 children and adults at the movie.

Agreeting card company can produce a box of cards for $7.50. if the initial investment by the company was $50,000, how many boxes of cards must be produced before the average cost per box falls to $10.50?

Which inequality has a dashed boundary line when graphed ?