To find the slope of the line, first start with a point on the graph.
Let's use the point (0,3) which we call point A.
The other point we will call point B.
Now remember that slope can be found using the ratio rise/run
between any two points that are on that line.
To get from point A to point B along this line, we must
first go down 3 units so we say that our rise is -3.
From there we move 1 unit to the right so our run is 1.
So our slope or rise/run is -3/1 which reduces to -3.