There is a very long line that has been forming all night to buy tickets for a concert. At 7:00 am no more people were allowed to join the line. At 8:00 am two ticket windows opened serving the customers in the line. At 5:00 pm, the last person was done buying his tickets. Assuming the rate that each window helped every customer was the same, how much shorter, in hours, would this process have taken had there been one more window open all day?