Answer:
11,040
Explanation:
multiply 60 seconds by 60 to get the number of seconds in an hour, which is 3,600 seconds.
then multiply 3,600 by three to get 10,800, as the number of seconds in three hours.
After this, divide 60 by 15 to get how long one fifteenth of an hour is, which turns out to be four minutes even.
Then multiply four minutes by 60 to get the number of seconds in that time, giving you 240 seconds.
Finally, add the 240 seconds we got from the four minutes to the 10,800 seconds we got in three hours to get a final answer of 11,040 seconds.
Cheers, I hope it helps!