There are 1760 yards in one mile and the rink is 250 yard in perimeter.
This means 3 miles is 5280 yards.
If Sam has already gone around the whole rink 6 times, that means he was traveled a total of 1500 yards.
Sam has 3780 more yards to travel 3 miles.
This means he needs to do 15.12 more laps around the rink. Or 16 if you are rounding.
Hope this helps! :)