Answer:
 miles
Explanation:
Total length of the trail = 
 miles = 
 miles
She ran the first 
 of the distance i.e.
The distance for which she ran = 

Remaining distance = Total length of trail minus the distance for which she has already run = 
 miles
Given that: After running, Annie has to walk due to steep nature of the trail, So, Annie walked for 
 of the remaining distance.
The distance for which Annie walked = 
 Remaining distance
The distance for which Annie walked = 
 
 = 
 miles
So, the answer is: 
 miles