Distance covered by Mario in 6 hours is 330 miles. Then, Average speed of Mario is 330 miles divided by 6 hours = 55 miles per hour so to drive a total distance of 715 miles, it would take him ( 715 miles divided by 55 miles per hour) hours i.e., 13 hours so Mario will have to drive for 7 more hours to complete a total distance of 715 miles.