A police car starts chasing a fugitive in a BMW 3 hours after the BMW escapes…

A police car starts chasing a fugitive in a BMW 3 hours after the BMW escapes from the scene of crime at 10 AM.The BMW drives for 10 km through the crowded roads of Shanghai and then drives into a highway, where the traffic allows vehicles to move twice as fast. After a while, the police car finally catches up with BMW after a chase that lasted 4 hours. By this time the moon was up in the sky for 4 hours. If the average speed of the police car is 83 kmph, then the average speed of the BMW (in kmph) is