Solve the Equation Ax = B by Using the LU

Solve the equation Ax = b by using the LU factorization given for A.
- $$\begin{array} { l } A = \left[ \begin{array} { r r r } 3 & - 1 & 2 \\- 6 & 4 & - 5 \\9 & 5 & 6\end{array} \right] , \mathbf { b } = \left[ \begin{array} { r } 6 \\- 3 \\2\end{array} \right] \\A = \left[ \begin{array} { r r r } 1 & 0 & 0 \\- 2 & 1 & 0 \\3 & 4 & 1\end{array} \right] \left[ \begin{array} { r r r } 3 & - 1 & 2 \\0 & 2 & - 1 \\0 & 0 & 4\end{array} \right]\end{array}$$

A) $\mathbf { x } = \left[ \begin{array} { r } 49 \\ - 38 \\ 32 \end{array} \right]$
B) $\mathbf { x } = \left[ \begin{array} { c } 22 \\ - 7 \\ 15 \end{array} \right]$
C) $\mathbf { x } = \left[ \begin{array} { c } 10 \\ - 2 \\ - 13 \end{array} \right]$
D) $\mathbf { x } = \left[ \begin{array} { r } 25 \\ - 58 \\ 51 \end{array} \right]$