Answer:
14 miles
Explanation:
182/13 = 14 miles
Assuming each horse was only ridden once
then a total of 16 horses were ridden for a total of 182 miles
182 miles /13 horses = 14 miles horse
Of course, if each horse was ridden more than once before being replaced the distance between replacements could be reduced.
Note that the fact that there were 3 riders is irrelevant.