Ok; Since we know that in 45 min, she can walk 3 miles, we can divide it to see how many minutes it takes for her to walk 1 mile. 45 divided by 3 is 15. Which means it takes her 15 minutes to walk 1 mile. If we look back at the beginning, it says she takes 15 minutes. Now that we know that it takes her 15 minutes to walk 1 mile, the answer is that it takes her 1 mile to walk to the library.
