Answer:
7.2 miles
Explanation:
Janet hikes a trail 3.6 miles long each day. Considering the forth and back path, she trails 2*3.6= 7.2 miles.
Since she has hiked 5 days in the past week, she has hiked 5*7.2 = 36 miles.
The question does not specify if the path back is to be considered. If not, then the total distance traveled is 3.6*5 = 18 miles.