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 number windows. define the variable used in the equations.

part b: which company would charge less for cleaning 8 windows? justify your answer.

part c: how much money is saved by using the services of company b instead of company a to clean 6 windows?