Please, post only one question at a time.
The line passing through (1,4) and (-4,-1) has the following slope:
-1 - 4 -5
m = ------------ = -------- = +1
-4 - 1 -5
Find the slope of the line passing thru the other set of points. Graph both lines. What do you see? Do the 2 lines have any particular relationship to one another?
