The black line crosses the y-axis at (0, 2), which is the y-intercept.
(0, 2) and (2, 1) are on the line. Going from the first point to the second, we see that x (the run) increases by 2 and y (the rise) decreases by 1. Thus, the slope of the black line is m = rise / run = -1/2. This is the slope of the line.
