A small 3000-lb airplane and a 6000-lb helicopter flying at an altitude of 3600 ft are observed to collide directly above a tower located at O in a wooded area, four minutes earlier the helicopter had been sighted 5.5 mi due west of the tower and the airplane 10 mi west and 7.5 mi north of the tower. As a result of the collision the helicopter was split into two pieces, H1 and H2, weighing 2000 lb and 4000 lb, respectively; the airplane remained in one piece as it fell to the ground. Knowing that the two fragments of the helicopter were located at points H1 (1500 ft, -300 ft and H2 (1800 ft, -1500 ft), respectively, and assuming that all pieces hit the ground at the same time, determine the coordinates of the point A where the wreckage of the airplane will be found.