Maria is comparing the prices of two window cleaning companies. Company A charges $6 per window and an additional $12 as service charges. Company B charges $5 per window and an additional $15 as service charges.

Part A: Write equations to represent Company A's and Company B's total charges for cleaning a certain number of windows. Define the variable used in the equations. (4 points)

Part B: Which company would charge less for cleaning 8 windows? Justify your answer. (3 points)

Part C: How much money is saved by using the services of Company B instead of Company A to clean 6 windows? (3 points)