Use a Graphing Utility to Solve the System of Linear $$\left\{ \begin{array} { r r } 9 x + 3 y - z = & 15 \\x + 7 y - 6 z = & - 18 \\7 x + y + z = & 21\end{array} \right.$$

Use a graphing utility to solve the system of linear equations and give the solution of the system.
- $$\left\{ \begin{array} { r r } 9 x + 3 y - z = & 15 \\x + 7 y - 6 z = & - 18 \\7 x + y + z = & 21\end{array} \right.$$

A)

$$x = \frac { 5 } { 3 } , y = - \frac { 59 } { 20 } , z = 9$$

B)


$x=1, y=5, z=9$

C)

$$x = 9 , y = 5 , z = 1$$
D)

$$x = \frac { 5 } { 2 } , y = - \frac { 11 } { 2 } , z = 9$$