Final answer:
There were 52 earthquakes in the U.S. in those two years.
Step-by-step explanation:
The first year, there were 24 earthquakes in the U.S. The next year, there were 28 earthquakes. To find the total number of earthquakes in those two years, you just need to add the number of earthquakes in each year together. So, 24 + 28 = 52. Therefore, there were 52 earthquakes in those two years.
Learn more about addition of numbers