Two cars, Car A and Car B, are moving away from an intersection of two highways(assume that the highways are perpendicular to each other). If Car A travels at 35 miles/hour while Car B travels at 30 miles/hour, how fast is the distance between the two cars increasing when Car A is 3 miles and Car B is 4 miles away from the intersection? 40 miles/hour 45 miles/hour 50 miles/hour 52 miles/hour