The average airspeed velocity of an unladen (european swallow is approximately 24 mph. at this rate, how many hours will it take the swallow to fly from appin to glen coe (about 18 miles?

So we want to know how much time would take European swallow to fly 18 miles if its average speed is 24 mph. So the time it takes to fly 18 miles if the average speed is 24 mph is t=distance/velocity or t=s/v. So now we input the numbers: t=18/24=3/4=0.75 hours. So the correct answer is 3/4 of an hour. Or 0.75 h is 0.75*60 min= 45 mins or three quarters of an hour. 

I’m not sure how this works