Essentially, slope is rise/run. Rise is how many units up the graph, and run is how far to the left or right it goes. Rise will be negative if it's going down, and run will be negative if it's going left. There's two ways to find the slope in this case.
1. Stick to the more visual aspect of it, and count how many units up from one point to the next point. Point (1,2) is 2 units up from point (0,0). Then you count how many units right or left it goes. In this case, it's 1 towards the right. This means the rise/run comes out to be 2/1, which means the slope=2.
2. Look at the equations. y=mx+b is the linear format for these lines. y is the y coordinate, m is the slope, x is the x coordinate, and b is the y intercept (the point where x=0). These two lines have shared slope values, which means the slope for both of them is 2.
