Nolan rides his bike 63 miles in 270 minutes. what is his average speed in miles per hour?

Here, to find the average rate of change, you would simply divide 270 by 63. And when that is done, you would get a long decimal. 4.285714285714286

And since you obviously can't put in such a long decimal as your answer, you would round it instead. Once rounded, you would end up with 4.29 (because the number after 8 is five, which rounds up, which would turn the 8 to 9.)