salma is deciding between two truck rental companies. company a charges an initial fee of $45 for the rental plus $2.50 per mile driven. company b charges an initial fee of $100 for the rental plus $1.50 per mile driven. let aa represent the amount company a would charge if salma drives xx miles, and let bb represent the amount company b would charge if salma drives xx miles. write an equation for each situation, in terms of x,x, and determine which company would be cheaper if salma needs to drive 60 miles with the rented truck.