Solve the System Using Gaussian Elimination $( x , y )$

Multiple Choice

Solve the system using Gaussian elimination. If $( x , y )$ is the solution to the system, give the value of $2 x - y$ .
$$\left\{ \begin{array} { c } x + y = 24 \\x - 2 y = - 3\end{array} \right.$$

A) $\quad 19$
B) $\quad 20$
C) 21
D) 24
E) $\quad 18$