Isaac is deciding between two truck rental companies. Company A charges an initial fee of $75 for the rental plus $1.50 per mile driven. Company B charges an initial fee of $45 for the rental plus $2.50 per mile driven. Let AA represent the amount Company A would charge if Isaac drives xx miles, and let BB represent the amount Company B would charge if Isaac 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.