That is correct as 17 is a prime number and can only be divided by 1 and itself
Hope this helps :)
You do distance over time to get the rate, so you'd do 27/2= 13.5mph then divide that in half since you're asking for the distance traveled in half that hour so you do 13.5/2 and you get 6.75 miles traveled in half and hour.
The answer is D I think. I'm not really good with math oof