Q84. Let a conic $C$ pass through the point $( 4 , - 2 )$ and $P ( x , y ) , x \geq 3$, be any point on $C$. Let the slope of the line touching the conic $C$ only at a single point $P$ be half the slope of the line joining the points $P$ and $( 3 , - 5 )$. If the focal distance of the point $( 7,1 )$ on $C$ is $d$, then $12 d$ equals $\_\_\_\_$\\