Let the plane passing through the point (-1, 0, -2) and perpendicular to each of the planes 2 x+y-z=2 and x-y-z=3 be a x+b y+c z+8=0. Then the value…

Let the plane passing through the point (-$\displaystyle 1$, $\displaystyle 0$, -$\displaystyle 2$) and perpendicular to each of the planes $\displaystyle 2 x+y-z=2$ and $\displaystyle x-y-z=3$ be $\displaystyle a x+b y+c z+8=0$. Then the value of $\displaystyle \mathrm{a}+\mathrm{b}+\mathrm{c}$ is equal to :