The b in 'y=mx+b' is 2 because thats where the line crosses on the y-axis. When finding the slope which is m in this situation keep in mind, rise over run. Now obviously this line is descending so we have to count down to where the next solid point is. In this case we count down to 3. Then we run or go over to the point which is 4 spaces over. Since our line is descending its a negative.
