first trail ... 5 1/3 = 16/3 miles
second trail ... 1 3/4 = 7/4 times as long as the first
We would like to know how many miles Jamal hiked. To answer this question, we have to add miles from the first trail and miles from the second trail.
But first we have to calculate how long was the second trail:
7/4 * 16/3 = 7*4/3 = 28/3 = 9 1/3 miles
Now, we have to add miles from both of the trails:
16/3 + 28/3 = 44/3 = 14 2/3 miles
Result: Jamal hiked 14 2/3 miles.