Tim owns a clothing store where he designs pairs of shorts, S, and T-shirts, t. He sells the shorts for 12 and the t-shirts for 8 each. Tim can work 18 hours a day, at most. It takes him 30 minutes to design a t-shirt and 45 minutes to design a pair of shorts. He must design at least 12 items each day, but he cannot design more than 30 items in one day. Which set of inequalities below represents this scenario?