Consider the plane $2 x_{1}-3 x_{2}+4 x_{3}=0$ with basis $$\$$ consisting of vectors $\left[\begin{array}{r}8 \\ 4 \\ -1\end{array}\right]$ and $\left[\begin{array}{r}5 \\ 2 \\ -1\end{array}\right] .$ If $[\vec{x}]_{8}=$
$\left[\begin{array}{r}2 \\ -1\end{array}\right],$ find $\vec{x}$