Question 1166094
The small boat has an 18 mile head start 
The other boat is moving 18 miles per hour faster.
They will catch up in 1 hour.

d=velocity*time

small boat has gone 9t miles when caught
the larger boat goes the same distance or 27(t-2) miles
9t=27t-54
-18t=-54
t=3 hours, so large boat goes for 1 hour before they are alongside.
The answer is 1 hour, which the above stated,