to find the slope of a line you haev to get 2 points from the line and put it in this formula y2-y1/x2-x1
E.J. if your point are (5,-1) and (1,-5) you would plug them in like this
-5+1/1-5 now add or subtract to get -4/-4 now divide to get 1
(note that when you have 2 negatives it changes to a positive that is why my number 1 changed from a -1 to a positive 1, this alos aplies when dividing, that is why when I divide the -4/-4 i got 1 and not -1)
Hope this helped