If the foot of the perpendicular drawn from (1, 9, 7) to the line passing through the point (3,2,1) and parallel to the planes x+2 y+z=0 and 3 y-z=3…

If the foot of the perpendicular drawn from ($\displaystyle 1$, $\displaystyle 9$, $\displaystyle 7$) to the line passing through the point $\displaystyle (3,2,1)$ and parallel to the planes $\displaystyle x+2 y+z=0$ and $\displaystyle 3 y-z=3$ is $\displaystyle (\alpha, \beta, \gamma)$, then $\displaystyle \alpha+\beta+\gamma$ is equal to