Annie needs $30 to buy a coat she has saved $12 and plans to work as a baby siter to earn $6 per hour which inequality shows the minimum number of hours, n, that annie should work as a babysitter to earn enough to buy a coat?
a 12 + 6n ≤ 30, so n ≤ 3
b 12 + 6n ≥ 30, so n ≤ 3
c 6n ≥30 + 12, so n ≥ 7
d 6n ≤30 + 12, so n ≤ 7