Part 1.
The slope is found by the change in Y over the change in X.
In the picture they are finding the difference between the X and Y of each point. They have x1 - y1 over x2-y2, when it should be y2-y1 / x2 - x1.
Part 2:
Slope = Change in Y over change in X:
(4 - 6) / (0 - -2) = -2 / 2 = -1
Slope = -1
Using the point (0,4) tells you the Y-intercept, which is the Y value when x is 0. The Y intercept is added to the slope when writing the equation of a line in point slope form.
The equation is y = -x +4
Part 3:
Find two points on the line by replacing X with 0 and solving for Y and then replace Y with 0 and solve for X. This gives you the X and Y intercepts. Once you have those two points, put them on a graph and then draw a straight line through both dots.
