Question 311625
Garys height above water = 2 meters.( vertical height)
rope tied to a boat = 5.2 meters.( hypotenuse)

sqrt ((5.2)^2 -(2)^2) = distance of boat from foot of the dock
=4.8 meters

..
the rope is pulled in by 2.3 meters.
Now the rope's length to the boat = 2.9 meter.
this is the hypotenuse.
.
vertical height = 2 meters.

sqrt ((2.9)^2-(2)^2)= 2.1
Now the boat is 2.1 meters from the foot of the dock.
The boat has moved from 4.8 meters to 2.1 meters  from the foot of the dock
So he has moved the boat by 2.7 meters.