step-by-step process find the slope first using (y-y)/(x-x) (4-(-5))/(-1-2) = 9/(-3) m = -3
then use one of the points to find the y-intercept by putting it in y=mx+b, substituting m with -3 (aka the slope) as well 4 = -3(-1) + b 4 = 3 + b 4 - 3 = 3 + b - 3 1 = b