Solve using substitution please help!!!

Answer:
The solution of the system is: A
Step-by-step explanation:
[tex]\left \{ {{12x-9y=30} \atop {6x+15y=54}} \right. \\\left \{ {{x=\frac{30+9y}{12} } \atop {6x+15y=54}} \right. \\\left\{ {{x=\frac{30+9y}{12}} \atop {6*\frac{30+9y}{12}+15y=54}} \right. \left \{ {{x=\frac{30+9y}{12}} \atop {15+\frac{9}{2}y+15y=54 }} \right. \\\left \{ {{x=\frac{30+9y }{12}} \atop {y(\frac{9}{2}+15) )= 39}} \right. \\\left \{ {{x=4} \atop {y=2}} \right.[/tex]