Hey there!
To start, you must use the distance formula which is [tex]\sqrt{(x1-x2)^{2}+(y1-y2)^{2} }[/tex].
x1 and x2 are the x coordinates of the points (it does not matter which one you assign to be x1 and x2) and y1 and y2 are the y coordinates (also does not matter which one you assign to be y1 and y2).
Now, set up your formula and simplify:
[tex]\sqrt{(x1-x2)^{2}+(y1-y2)^{2} }[/tex]
[tex]\sqrt{(-12-13)^{2}+(6-8)^{2} }[/tex]
= [tex]\sqrt{629}[/tex] ≈ 25.0799
