A body travels 10 meters during the first 5 seconds of its travel, and it travels a total of 30 meters over the first 10 seconds of its travel. What is
its average speed during the time from t 5 seconds to t - 10 seconds?
A. 2 meters/second
В. 3 meters/second
С. 4 meters/second
D. 5 meters/second
E. 6 meters/second