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. Lets 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?