What are the keywords to a word problem?

I need to know the key words to solving a word problem in math. More specifically what I need to do to this problem.'The Appalachian National Scenic Trail is the longest marked walking path in the United States. It extends through 14 states for about 2000 miles.Last year, Carla hiked 1/5 of the trail. How many miles of the trail did she hike?'