Tyler works in retail where she earns $10.50 per hour. She also earns $15 for every new credit account she gets customers to open and she gets a weekly stipend of $50 for clothing. Tyler knows her weekly earnings can be shown with the following expression:

10.50h + 15c + 50

Part A: Identify a coefficient, a variable, and a constant in this expression. (3 points)
Part B: If Tyler works for 37 hours and opens 12 new credit accounts, how much does she earn? Show your work to receive full credit. (4 points)
Part C: If Tyler gets a raise and begins earning $11.25 per hour, would the coefficient, variable, or constant in the expression change? Why? (3 points)