Question 676495
60 mph and 45 mph. 

Here's how I came up with that answer. First, realize that 45 miles over a period of 3 hours, is equivalent with 15 miles over 1 hour. Thus, one car was going 15 mph faster than the other car and was also going 4/3 its speed. 

60 and 45 meet those criteria perfectly, as 60 is 15 greater than 45, and over a period of 3 hours, the car going 60mph will be 45 miles further on the road than the car going 45 mph. Plus, 60 is 1 1/3 greater than 45, so it verifies that this is indeed the correct answer.