Mia is deciding between two truck rental companies. Company A charges an initial fee of $100 for the rental plus $1.50 per mile driven. Company B charges an initial fee of $40 for the rental plus $3 per mile driven. Let AA represent the amount Company A would charge if Mia drives xx miles, and let BB represent the amount Company B would charge if Mia drives xx miles. Write an equation for each situation, in terms of x, x, and determine the interval of miles driven, x, x, for which Company A is cheaper than Company B.