$(a)\;\large\frac{x-b}{a}=\large\frac{y-1}{1}=\large\frac{z-d}{c} \qquad(b)\;\large\frac{x-b-a}{a}=\large\frac{y-1}{1}=\large\frac{z-d-c}{c} \qquad(c)\;\large\frac{x-b}{b}=\large\frac{y-0}{1}=\large\frac{z-c}{d}\qquad(d)\;\large\frac{x-b-a}{b}=\large\frac{y-1}{0}=\large\frac{z-d-c}{d}$