A north-south highway A and an east-west highway intersect at a point P. At 10 AM an automobile crosses P traveling north on highway A at a speed of 50 mi/hr. At that same instant, an airplane flying east at a speed of 200 mi/hr and an altitude of 2,640 ft is directly above the point on highway B that is 100 miles east of P.
If the airplane and the automobile maintain the same speed and direction, at what rate is the distance between them changing at 10:15 AM?