Solve the System by Using the Inverse of the Coefficient $$\begin{aligned}x + 3 y & = - 8 \\21 x + 6 y & = 3\end{aligned}$$

Multiple Choice

Solve the system by using the inverse of the coefficient matrix.
- $$\begin{aligned}x + 3 y & = - 8 \\21 x + 6 y & = 3\end{aligned}$$

A) $\{ ( - 3,1 ) \}$
B) $\{ ( 1 , - 3 ) \}$
C) $\{ ( - 1,3 ) \}$
D) $\{ ( 3 , - 1 ) \}$