Hey there! I'm happy to help!
We see that Noah rides his motorcycle 90 miles is 2 hours and 30 minutes, which is 150 minutes. We want to find his mph. To find this his mph, we want to find how far he has gone in one hour.
How much bigger is 150 than 60?
150/60=2.5
150 is 2.5 times bigger than 60. This means that we need to divide 90 by 2.5 to figure out how far Noah rode in 1 hour.
90/2.5=36
Therefore, Noah's average speed is 36 mph.
Have a wonderful day! :D