Let the equation of plane passing through the line of intersection of the planes $x+2 y+a z=2$ and $x-y +z=3$ be $5 x-11 y+b z=6 a-1$. For $c \in Z$, if the distance of this plane from the point $(a,-c, c)$ is $\frac{2}{\sqrt{a}}$, then $\frac{\mathrm{a}+\mathrm{b}}{\mathrm{c}}$ is equal to-
