已知向量 ${ }^{e_{1}}, e_{2}$ 不共线, 实数 $B C_{\text {满足 }}(2 x-3 y) e_{1}+(3 x-4 y) e_{2}=6 e_{1}+3 e_{2}$, 则 $x+y=$
$\because$ 向量 ${ }^{e_{1},},{ }^{G_{1}}$ 不共线,

$\therefore\left\{\begin{array}{l}2 x-3 y=6 \\ 3 x-4 y=3,\end{array}\right.$ 解得 $\left\{\begin{array}{l}x=-15, \\ y=-12,\end{array} \therefore x+y=-27\right.$.