Angela needs $60 to buy a series of books. She has saved $24 and plans to work as a babysitter to earn $4 per hour. Which inequality shows the minimum number of hours, n, that Angela should work as a babysitter to earn enough to buy a series of books?
24 + 4n ≤ 60, so n ≤ 9
24 + 4n ≥ 60, so n ≥ 9
4n ≥ 60 + 24, so n ≥ 21
4n ≤ 60 + 24, so n ≤ 21