The fastest fish, the sailfish, can swim 1.2 x 100 km/h. Suppose you have a friend who lives on an island 16 km away from the shore. If you send a message using a sailfish as a messenger, how long will it take for the message to reach your friend?

The way the speed was given is a bit weird... but that doesn't change the fact that:

Speed = Distance / Time

Rearranging gives you:

Time = Distance / Speed

This should be easy enough to work out.