the question states that Nancy has to run a trail that is 5.3 miles long.
After 20 minutes she has run and covered 1.45 miles off the trail.
total trail - 5.3 miles long
distance covered - 1.45 miles
Therefore the number of miles that nancy has to cover to get to the end of the trail -x
x = 5.3 - 1.45
= 3.85 miles
therefore 3.85 miles left to run to get to the end of the trail