Two rockets are to be launched at the same time from NASA headquarters in Florida, and are to meet at a space station many miles from Earth. The first rocket is to travel at 18,000 miles per hour and the second rocket will travel at 15,000 miles per hour. If the first rocket is scheduled to reach the space station 0.5 of an hour before the second rocket, how far is the space station from NASA headquarters? the distance is___(mi)