Ans: B
$\left\{ \begin{array}{ll}
6x – 7y = 40 & \ldots \unicode{x2460} \\
2x + 11y = 40 & \ldots \unicode{x2461}
\end{array} \right.$
$\left\{ \begin{array}{ll}
6x – 7y = 40 & \ldots \unicode{x2460} \\
2x + 11y = 40 & \ldots \unicode{x2461}
\end{array} \right.$
$\unicode{x2460} – \unicode{x2461} \times 3$, we have
$\begin{array}{rcl}
-7y – 33y & = & 40 – 120 \\
-40y & = & -80 \\
y & = & 2
\end{array}$
