The answer is amortization
If you plug in h, the answer would be 13-9 which is 4.

P.S. Hello from Russia :^)
The answer would be 40 days
We achieve this answer by dividing the distance of the trip, 30 miles, by the distance traveled per day, 3/4 miles.
First, you have to find the median, which is the number in the middle: 25
Then cut the data in half by the median, so your new data sets are
15,29,20
and
31,38,41
Now you find the median of both of those sets, which is 29 and 38.
The interquartile range is the difference between the numbers, so 38-29 = 9.