Let A, B and C be three 2 × 2 matrices with real entries such that B=(I+A)^-1 and A + C = I. If BC = [1, -5; -1, 2] and CB [x_1; x_2] = [12; -6],…

Let $\displaystyle A, B$ and $\displaystyle C$ be three $\displaystyle 2 \times 2$ matrices with real entries such that $\displaystyle B=(I+A)^{-1}$ and $\displaystyle \mathrm{A}+\mathrm{C}=\mathrm{I}$. If $\displaystyle \mathrm{BC}=\left[\begin{array}{cc}1 & -5 \\ -1 & 2\end{array}\right]$ and $\displaystyle \mathrm{CB}\left[\begin{array}{l}x_1 \\ x_2\end{array}\right]=\left[\begin{array}{c}12 \\ -6\end{array}\right]$, then $\displaystyle x_1+x_2$ is