Question 888742
{{{y=mx+b}}}


Point on graph, (0,b).


Move m units down and -1 unit to the left for another point; maybe also do this again;  draw line to connect the points. 
OR, 
from (0,b), move m units up, and 1 unit to the right... , draw line connecting the points.


You make account properly for the sign of m.