Suppose parametric equations for the line segment between $(2,-8)$ and $(2,1)$ have the form:

$x=abt$

$y=cdt$

If the parametric curve starts at $(2,-8)$ when $t=0$ and ends at $(2,1)$ at $t=1,$ then find $a,b,c$ and $d.a=$

$b=$

$c=$

$d=$