The number of hours, y, it takes to drive from town P to town Q is inversely proportional to the average speed of a car, x miles per hour. It takes Jeremiah 3 1/2 hours to drive from town P to town Q at an average speed of 60 miles per hour on a particular day. How long will it take Jeremiah to travel from Town P to Town Q if his average driving speed is 70 miles per hour instead?