Answer:
8 kilometers per hour.
Explanation:
1-If you multiply the hours of the trip back (which is 4 hours) and the kilometer per hour (6 km/h) you will get 24.
2-Do the same thing with the trip there and you will get 3 hours multiplied by *blank* equals 24.
3-the blank is 8 kilometers per hour. And I wrote equal 24 to mean that the distance to Guam was 24 kilometers.