To solve this, the best way is to imagine a right triangle. If you conect Hillburn and Dunford with a straight line, and then complete the right triangle, we can use the phytagorean theorem to fin the value of the distance.
H is Hillburn and D is Dunford.
now we count the units that separe H from D, horizontally. H is in x=-3 and D is in x=2. So the distance in x is 5.
For the distance vertically, H is in y=2 and D=-2. The distance in y is 4
Now we can use Pythagoras
So the distance is 6.4 miles,