If the water comes in at 10 gallons/min, then the boat will sink in 3 mins.

They are 1 mile away from shore, so it will take 15 mins to get to shore.

If it takes 15 mins to get to shore, then you can't have the boat take on any more than 2 gallons/min (Because 2x15 = 30).

So LeRoy will have to remove water at the rate of 8 gallons/min.