Explanation:
To find the Slope of each line, pick two points you can clearly identify on each graph. The first graph has a point (-5,5) and (4,-5). Using these two points find the difference of the y coordinates divided by the difference in the x coordinates, like this:
5 - (-5). = 10
-5 - 4 = - 9
So the Slope is - 10/9
Same steps for all. Your equation is
(y1 - y2) / (x1 - x2)