Clyde drove 30 miles in 20 minutes and then drove an additional 10 miles in 10 minutes. what is the average speed for the entire trip?

Add up the number of minutes
20 minutes + 10 minutes = 30 minutes
Add up the number of miles
30 miles + 10 miles = 40 miles
Average speed: 40 miles in 30 minutes.
Other ways to write this: 80 mph, 4/3 mi/min