What is the slope of (-6,8) and (2,-2)

Slope equals change in y divided by change in x.  You have two points, (-6,8) and (2,-2)

Slope equals (y2-y1)/(x2-x1), order does not matter only that we use the same point for y2s and x2s

(8--2)/(-6-2)=10/-8=-5/4  Yes that is negative :)

We could also say:

(-2-8)/(2--6)=-10/8=-5/4

As long as you are dividing change in y by change in x you are going to find that you get the same slope.