Y-INTERCEPT: It's called the "y intercept" and it's the y value of the point where the line intersects the y- axis. For this line, the y-intercept is "negative 1." You can find the y-intercept by looking at the graph and seeing which point crosses the y axis. This point will always have an x coordinate of zero.
SLOPE:The slope will be the same for a straight line no matter which two points you pick as you know. All you need to do is to calculate the difference in the y coordinates of the 2 points and divide that by the difference of the x coordinates of the points(rise over run). That will give you the slope.
The Y intercept is where the line crosses the Y axis on a graph. On an equation in the form Y=Mx+B it would be the +B. On an equation the slope is always the Mx
Supplementary angles are two angles whose sum equal to 180 degrees. Vertical lines are the opposite angles in the intersecting lines. Thus, each of your angles must be 90 degrees. Just simply draw two straight and intersecting lines.
