for the number before x you would look for the rise over the run. in this case you can see that there is an intersection at (-2,0) and (0,1) you find the difference ox each so you have 2/1 or just 2 you can tell that the line is going up so it is positive. for the addition part look at where the y intercept is in this case it is at positive one. this makes your equation y=2x+1
