While the question gives us the coordinates for 4 points, we only need 2. You can choose any pair of points and the process I will demonstrate will still be applicable and you will get the same results. I will just pick the first two points.
Points: (4,-4) and (8,-1)
As you may already have known, the first number in the parentheses is the x value and the second number is the y value. In order to solve for the slope of the line created by the two points, we must find the difference between the y values of the two points and divide by the difference between the x values of the two points. This can more commonly be called delta y over delta x.
(y of point 1 - y of point 2)/(x of point 1 - x of point 2)
= (-4 + 1)/(4 - 8)
= (-3)/(-4)
=3/4
Slope = 3/4