David drove 70 miles in the first 1 ¾ hours of his trip. How much longer should it take him to drive an additional 120 miles if he drives at the same average speed?

Answer 1

To find the speed at which David is driving, we divide the distance he drove by the time it took him to drive that distance: 70 miles / (7/4) hours = 40 miles/hour
To find how long it takes him to drive an additional 120 miles at that speed, we divide the distance by the speed: 120 miles / 40 miles/hour = <<120/40=3>>3 hours. Answer: \boxed{3}.