Answer:
x=4 y=4
Step-by-step explanation:
Cut the -3y and the +3y because they are the opposite values, same numbers and variables. So then it becomes -3x=12
-9x=-24
From there you divide the -3 on both sides leading you with x=4. Then you substitute the x with 4 on the second equation. So then its -9(4)+3y=-24 (notice how I put the 3y in the place it was before). You will end up with -36+3y=-24. You add 36 on the negative and on the -24, ending with 3y=12. From there you divide 3 on both sides and y=4.