Hi there, to find the answer, we are going to need a equation. So, let's get started. I know that 1 mile equals 1,760 yards, I also know that Alex walked 1 mile in 15 minutes and Sally walked 2 miles in 24 minutes. So, Alex walked 1/4 of an hour and Sally walked 2/5 of an hour, there is 4 miles in 1 hour and 5 miles in 1 hour. We subtract 5 from 4 and we get 1.