​Use the Matrix Capabilities of a Graphing Utility to Solve $$\left\{ \begin{array} { l l } - 14 x + 14 y + 21 z & = 10 \\7 x - 7 y & = - 5 \\7 x + 28 z & = 20\end{array} \right.$$

Multiple Choice

​Use the matrix capabilities of a graphing utility to solve the following system of linear equations:​ $$\left\{ \begin{array} { l l } - 14 x + 14 y + 21 z & = 10 \\7 x - 7 y & = - 5 \\7 x + 28 z & = 20\end{array} \right.$$ ​

A) ​ $$\left[ \begin{array} { l } x \\y \\z\end{array} \right] = \left[ \begin{array} { c } \frac { 20 } { 7 } \\\frac { 25 } { 7 } \\0\end{array} \right]$$ ​
B) ​ $$\left[ \begin{array} { l } x \\y \\z\end{array} \right] = \left[ \begin{array} { c } \frac { 10 } { 7 } \\0 \\\frac { - 15 } { 7 }\end{array} \right]$$
C) ​ $$\left[ \begin{array} { l } x \\y \\z\end{array} \right] = \left[ \begin{array} { c } \frac { - 15 } { 7 } \\\frac { 10 } { 7 } \\\frac { 5 } { 7 }\end{array} \right]$$
D) ​ $$\left[ \begin{array} { l } x \\y \\z\end{array} \right] = \left[ \begin{array} { c } \frac { 5 } { 7 } \\\\\frac { - 20 } { 7 } \\\\\frac { 10 } { 7 }\end{array} \right]$$
E) ​ $$\left[ \begin{array} { l } x \\y \\z\end{array} \right] = \left[ \begin{array} { c } \frac { - 15 } { 7 } \\\\\frac { - 10 } { 7 } \\\\ \frac { 10 } { 7 }\end{array} \right]$$