There are 60 seconds in a minute and 60 minutes in an hour; 60 * 60 = 3,600 seconds in an hour. 3,600 / 45 seconds = 80. And to cross-check: 80 mph * 5,280 feet in a mile = 422,400 feet per hour / 60 = 7,040 feet per minute / 60 = 117 1/3 feet per second * 45 seconds = 5,280 feet in 45 seconds.