8. [-/1 Points] DETAILS TANAPCALC10 3.6.058. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER Docking a Boat A boat is pulled toward a dock by means of a rope wound on a drum that is located 3 ft above the bow of the boat. If the rope is being pulled in at the rate of 6 ft/s, how fast (in ft/s) is the boat approaching the dock when it is 18 ft from the dock? (Round your answer to one decimal place.) ft/5