Question 336753
Fast Boat:

rate = x - 4

time = 3

Slow Boat:

rate = x

NOTE: Time is measure in hours not minutes.

So, 30 minutes = 30/60 = 1/2 = 0.5.

The slow boat took 0.5 longer to reach the port.  This means the time for the slow boat is 3 hours + 0.5 or 3.5 hours.

Distances are equal because they are going to the same location leaving the same Island.

Here is your equation:

3(x + 4) = 3.5x

Can you find x now and then proceed to find the speed of each boat?  

HINT: Look above for the rate of each boat after finding the value of x.