the value of b is the y intercept or when the line crosses the y axis
this only happens when the value of x=0
so just look for the ordered pair in the table with x=0 and y=b
so if you had a table and saw
(0,3)
(x,y)
so the point where x=0 is at point (0,3) y=3
therefor b=3
basically look for the matching y value for when x=0