Mario drives at the average speed at all times with his old car. He makes it from point A direct to point C in 30 minutes; from point A through point B to point C in 35 minutes; and from point A through point D to point C in 40 minutes. Distance from point B to point C is 10 kilometers, the same distance from point C to point D. By the way angle C is 90 degrees. Points A, B, C and D are 4 corners of a quadrilateral and labeled in a clockwise manner. How fast does Mario drive in km/hour?