If the equation of the parabola with vertex \( V\left(\frac{3}{2},\,3\right) \) and the directrix \( x+2y=0 \) is \( \alpha x^{2}+\beta y^{2}-\gamma xy-30x-60y+225=0 \), then \( \alpha+\beta+\gamma \) is equal to:
\( 8 \)
\( 6 \)
\( 7 \)
\( 9 \)