1. Start out with y=mx+b. 'm' is the slope and 'b' is the y intercept.
2. Find where the line hits the y-axis on the graph. This will be your Y-Intercept.
3. Find where your line hits the X-axis. Now, count up or down from the x-axis until you get to the height of the y-point. now count across. Down/Up Divided by Across. This is your slope.
For Example, say that the line hits the Y-Axis at 4, and the line hits the X-Axis at -8. Count up from -8 till you get to the height of 4. It is 4. Now count across from that height. It is 8. Now, just put 4 on top of 8, to get 4/8. Simplify to 1/2. That is your slope. And since the line hit the Y-Axis at 4, 4 would be your Y-Intercept. Your final formula would be:
y=1/2x+4
