The distance is 5 MILES. There is a difference of 5 MILES between the two coordinates. The two coordinates are (4, -6) and (9, -6) and you can see that the second part of the coordinates are the same, so you dont have to worry about those. But there is a difference between 5 and 9, and the difference between them is 5.
And since you were asked to answer in miles, there is a difference of 5 MILES between the two coordinates.