Slope is the rise/run of the line. With the rise being how far apart the two points are on the y axis, and the run being how far apart the two points are on the x axis.
In this case, the first point is 6 units down from the other and 4 units over from it. (6/4) then from there you would simplify your fraction. (Both numerator and denominator can be divided by 2).
Your slope in total is 3/2. Hope this helped.