Question 921006
(0,b) and 
(-1,b-m)   m ={{{(y[1] - y[2])/(x[1] - x[2] )}}} slope = m/1
***Using point-slope form, {{{y - y[1] = m(x - x[1])}}}P(0,b)
y - b = m(x-0)
y = mx + b