I have to solve these systems in succession, and I don't know how:

$\displaystyle \left[ \begin {array}{ccc} 0&0&0\\\noalign{\medskip}-1&1&-1\\\noalign{\medskip}0&1&-1\end {array} \right]P = \left[ \begin {array}{c} 0\\\noalign{\medskip}1\\\noalign{\medskip}1

\end {array} \right]$

$\displaystyle \left[ \begin {array}{ccc} 0&0&0\\\noalign{\medskip}-1&1&-1\\\noalign{\medskip}0&1&-1\end {array} \right]Q = P$

I need P and Q