the b is the y intercept. this is where the line cuts through the y axis. you can see that it is going through the y axis at -2.
now look for your slope. I use rose over run. you can see that the line intersects at (4,-1)
"rise" is how far up or down to your next point."run" is how far left your right your next point is. in this case, the next point is 1 up and 4 to the right of a point. this translates to 1/4. this is a positive slope because your line goes upwards from left to right.
