The answer is b -1/2 because you have your formula for slope which is m=y2-y1 over x2-y1 and if you plug in your coordinates (1,1) (3,0) you get 0-1 for the y and 3-1 for the x and if you do that math you get -1/2 which is b anyways hope this helped as somone who is had at math this was the easiest lesson for me to understand so If I can help you in any way let me know !