Tamlin is learning to become a carpenter. She gets paid 12 per hour for building shelves and 14 per hour for building cabinets. She can work a maximum of 40 hours per week, and she would like to earn at least 250 this week. Let s represent the number of hours she spends building shelves and $c$ represent the number of hours she spends building cabinets. Which system of inequalities could be used to represent the given conditions?