Let a circle C of radius 5 lie below the $x$-axis. The line $L_1=4 x+3 y-2$ passes through the centre $P$ of the circle $C$ and intersects the line $L_2: 3 x-4 y-11=0$ at $Q$. The line $L_2$ touches $C$ at the point $Q$. Then the distance of $P$ from the line $5 x-12 y+51=0$ is
