What is the slope and b value of this graph?

Your B, or y-intercept, is 3(the y-intercept is the point at which your line crosses the y-axis)
Your slope is -2
-EXPLANATION-
When using the points given, (0,3) and (1,1) you will use the following formula:
M=y₂-y₁ / x₂-x₁
y2 being 1
y1 being 3
x2 being 1
x1 being 0
-solving-
M=1-3/1-0
M=-2/1
-2 divided by 1 is -2 making that your slope.
If you need it to be written in slope intercept form(y=mx+b), write it like this:
y=-2x+3
I hope this helped :)