If for some

If for some $\alpha$ and $\beta$ in $R$, the intersection of the following three places

$x+4 y-2 z=1$

$x+7 y-5 z=\beta$

$x+5 y+\alpha z=5$

is a line in $\mathrm{R}^{3}$, then $\alpha+\beta$ is equal to: